Semiconducting Compounds and Devices Incorporating Same

ABSTRACT

Disclosed are molecular and polymeric compounds having desirable properties as semiconducting materials. Such compounds can exhibit desirable electronic properties and possess processing advantages including solution-processability and/or good stability. Organic transistor and photovoltaic devices incorporating the present compounds as the active layer exhibit good device performance.

This application is a continuation of and claims priority to and thebenefit of patent application Ser. No. 14/298,523 filed Jun. 6, 2014 andissued as U.S. Pat. No. 9,240,556 on Feb. 19, 2016, which was adivisional of and claimed priority to and the benefit of patentapplication Ser. No. 13/429,005 filed Mar. 23, 2012 and issued as U.S.Pat. No. 8,754,188 on Jun. 17, 2014, which claimed priority to and thebenefit of Provisional Patent Application Ser. No. 61/467,015 filed onMar. 24, 2011 and Provisional Patent Application Ser. No. 61/466,801filed on May 9, 2011, the disclosure of each of which is incorporated byreference herein in its entirety.

This invention was made with government support under grant numberDE-SC0001059 awarded by the Department of Energy. The government hascertain rights in the invention.

BACKGROUND

A new generation of electronic, optical or optoelectronic devices suchas organic thin film transistors (OTFTs), organic light-emittingtransistors (OLETs), organic light-emitting diodes (OLEDs), or organicphotovoltaics (OPVs) are fabricated using organic semiconductors astheir active components. To be commercially relevant, these organicsemiconductor-based devices should be processable in a cost-effectivemanner.

Several p- and n-channel organic semiconductors have achieved acceptabledevice performance. For example, OTFTs based on acenes andoligothiophenes (p-channel) and perylenes (n-channel) exhibit carriermobilities (μ's)>0.5 cm²/V·s in ambient conditions. Furthermore, avariety of polymeric and molecular semiconductor materials incorporatingone or more fused thiophene rings have been synthesized and/or proposedas organic semiconductor building blocks, which includesnaphthodithiophene rings reported in Umeda, R., et al., Comptes RendusChimie (2009), 12(3-4), 378-384; Coropceanu, V., et al., Chemistry—AEuropean Journal (2006), 12(7), 2073-2080; Takahashi, T., et al., JP2010180151 A; Takimiya, K., et al., WO 2010058692 A1; Katakura, T., etal., JP 2006216814 A; and Katz, H. E., et al., U.S. Pat. No. 5,936,259A. Although many of these materials exhibit acceptable carriermobilities, improved processability is required for commercialfeasibility. For example, pentacene exhibits high hole mobility >5cm²/V·s with its highly crystalline nature, but cannot be processed viaprinting methodologies due to its insolubility.

Accordingly, the art desires new polymeric or molecular semiconductors,particularly those having well-balanced semiconducting properties andprocessing properties.

SUMMARY

In light of the foregoing, the present teachings provide polymeric andmolecular semiconductors that can address various deficiencies andshortcoming of the prior art, including those outlined above. Alsoprovided are associated devices and related methods for the preparationand use of these semiconductors. The present semiconductors can exhibitproperties such as excellent charge transport characteristics, lowtemperature processability, satisfactory solubility in common solvents,and processing versatility (e.g., printability). As a result, fieldeffect devices such as thin film transistors that incorporate one ormore of the present semiconductors can exhibit high performance, forexample, demonstrating one or more of large hole mobility, largeelectron mobility, low threshold voltages, and high current on-offratios. Similarly, other organic semiconductor-based devices such asOPVs, OETs, and OLEDs can be fabricated efficiently using the organicsemiconductor materials described herein.

Generally, the present teachings provide polymeric and molecularsemiconducting compounds comprising a5,10-dialkoxynaphtho[2,3-b:6,7-b′]dithiophene (NDT) moiety. For example,various embodiments of the present compounds can be represented by:

wherein R¹, R², Ar¹, Ar², Ar³, Ar⁴, π, m¹, m², m³, m⁴, p, x and y are asdefined herein.

The present teachings also provide methods of preparing such polymericand molecular semiconductor materials, as well as various compositions,composites, and devices that incorporate the polymeric and molecularsemiconductor materials disclosed herein.

The foregoing as well as other features and advantages of the presentteachings will be more fully understood from the following figures,description, examples, and claims.

BRIEF DESCRIPTION OF DRAWINGS

It should be understood that the drawings described below are forillustration purposes only. The drawings are not necessarily to scale,with emphasis generally being placed upon illustrating the principles ofthe present teachings. The drawings are not intended to limit the scopeof the present teachings in any way.

FIG. 1 illustrates four different configurations of thin filmtransistors: bottom-gate top contact (a), bottom-gate bottom-contact(b), top-gate bottom-contact (c), and top-gate top-contact (d); each ofwhich can be used to incorporate compounds of the present teachings.

FIG. 2 illustrates a representative structure of a bulk-heterojunctionorganic photovoltaic device (also known as solar cell), which canincorporate one or more compounds of the present teachings as the donorand/or acceptor materials.

FIG. 3 illustrates a representative structure of an organiclight-emitting device, which can incorporate one or more compounds ofthe present teachings as electron-transporting and/or emissive and/orhole-transporting materials.

FIG. 4 provides the UV/Vis absorption spectra (a) and cyclicvoltammograms (b) of NDT (4c) and BDT (7c).

FIG. 5 shows optical absorption spectra of polymer P1-P3 solutions inchloroform and films (a), P4-P5 solutions (b), and P4-P5 films (c).Polymer films were deposited on quartz substrate by spin coating fromchloroform solution (5 mg/mL).

FIG. 6 provides OFET response plots for polymer P4 a-based device: (a)transfer plot at VS_(D)=−100 V; and (b) output plot at V_(G) rangingfrom 0 V to −100 V.

FIG. 7 shows optical absorption spectra (A) of NDT(TDPP)₂ in chloroformsolution and as a film; (B) log scale θ-2θ X-ray diffraction pattern ofa drop cast NDT(TDPP)₂ film (from 10 mg·mL⁻¹ in chloroform) on aSi/SiO₂/HMDS substrate, annealed at 110° C.; (C) typical output and (D)transfer plot (V_(DS)=−100V) from a drop cast NDT(TDPP)₂ OFET annealedat 110° C.

DETAILED DESCRIPTION

The present teachings provide organic semiconductor materials thatinclude polymeric and molecular semiconductors and associatedcompositions, composites, and/or devices. Organic semiconductormaterials of the present teachings can exhibit semiconducting behaviorsuch as high carrier mobility and/or good current modulationcharacteristics in a field-effect device, light absorption/chargeseparation in a photovoltaic device, and/or chargetransport/recombination/light emission in a light-emitting device. Inaddition, the present materials can possess certain processingadvantages such as solution-processability. The materials of the presentteachings can be used to fabricate various organic electronic articles,structures and devices, including field-effect transistors, unipolarcircuitries, complementary circuitries, photovoltaic devices, and lightemitting devices.

Throughout the application, where compositions are described as having,including, or comprising specific components, or where processes aredescribed as having, including, or comprising specific process steps, itis contemplated that compositions of the present teachings also consistessentially of, or consist of, the recited components, and that theprocesses of the present teachings also consist essentially of, orconsist of, the recited process steps.

In the application, where an element or component is said to be includedin and/or selected from a list of recited elements or components, itshould be understood that the element or component can be any one of therecited elements or components, or can be selected from a groupconsisting of two or more of the recited elements or components.Further, it should be understood that elements and/or features of acomposition, an apparatus, or a method described herein can be combinedin a variety of ways without departing from the spirit and scope of thepresent teachings, whether explicit or implicit herein.

The use of the terms “include,” “includes”, “including,” “have,” “has,”or “having” should be generally understood as open-ended andnon-limiting unless specifically stated otherwise.

The use of the singular herein includes the plural (and vice versa)unless specifically stated otherwise. In addition, where the use of theterm “about” is before a quantitative value, the present teachings alsoinclude the specific quantitative value itself, unless specificallystated otherwise. As used herein, the term “about” refers to a ±10%variation from the nominal value unless otherwise indicated or inferred.

It should be understood that the order of steps or order for performingcertain actions is immaterial so long as the present teachings remainoperable. Moreover, two or more steps or actions may be conductedsimultaneously.

As used herein, a “polymeric compound” (or “polymer”) refers to amolecule including a plurality of one or more repeating units connectedby covalent chemical bonds. As used herein, a repeating unit in apolymer must repeat itself at least twice (as specified by its degree ofpolymerization) in the polymer. A polymer can be represented by thegeneral formula:

wherein M is the repeating unit or monomer. The degree of polymerization(n) can range from 2 to greater than 10,000, typically in the range from5 to about 10,000. The polymer can have only one type of repeating unitas well as two or more types of different repeating units. When apolymer has only one type of repeating unit, it can be referred to as ahomopolymer. When a polymer has two or more types of different repeatingunits, the term “copolymer” can be used instead. The polymer can belinear or branched. Branched polymers can include dendritic polymers,such as dendronized polymers, hyperbranched polymers, brush polymers(also called bottle-brushes), and the like. Unless specified otherwise,the assembly of the repeating units in a copolymer can be head-to-tail,head-to-head, or tail-to-tail. In addition, unless specified otherwise,the copolymer can be a random copolymer, an alternating copolymer, or ablock copolymer. For example, the general formula:

can be used to represent a copolymer of A and B having x mole fractionof A and y mole fraction of B in the copolymer, where the manner inwhich comonomers A and B is repeated can be alternating, random,regiorandom, regioregular, or in blocks.

As used herein, a “cyclic moiety” can include one or more (e.g., 1-6)carbocyclic or heterocyclic rings. The cyclic moiety can be a cycloalkylgroup, a heterocycloalkyl group, an aryl group, or a heteroaryl group(i.e., can include only saturated bonds, or can include one or moreunsaturated bonds regardless of aromaticity), each including, forexample, 3-24 ring atoms and can be optionally substituted as describedherein. In embodiments where the cyclic moiety is a “monocyclic moiety,”the “monocyclic moiety” can include a 3-14 membered aromatic ornon-aromatic, carbocyclic or heterocyclic ring. A monocyclic moiety caninclude, for example, a phenyl group or a 5- or 6-membered heteroarylgroup, each of which can be optionally substituted as described herein.In embodiments where the cyclic moiety is a “polycyclic moiety,” the“polycyclic moiety” can include two or more rings fused to each other(i.e., sharing a common bond) and/or connected to each other via a spiroatom, or one or more bridged atoms. A polycyclic moiety can include an8-24 membered aromatic or non-aromatic, carbocyclic or heterocyclicring, such as a C₈₋₂₄ aryl group or an 8-24 membered heteroaryl group,each of which can be optionally substituted as described herein.

As used herein, a “fused ring” or a “fused ring moiety” refers to apolycyclic ring system having at least two rings where at least one ofthe rings is aromatic and such aromatic ring (carbocyclic orheterocyclic) has a bond in common with at least one other ring that canbe aromatic or non-aromatic, and carbocyclic or heterocyclic. Thesepolycyclic ring systems can be highly π-conjugated and can be optionallysubstituted as described herein.

As used herein, “halo” or “halogen” refers to fluoro, chloro, bromo, andiodo.

As used herein, “oxo” refers to a double-bonded oxygen (i.e., ═O).

As used herein, “alkyl” refers to a straight-chain or branched saturatedhydrocarbon group. Examples of alkyl groups include methyl (Me), ethyl(Et), propyl (e.g., n-propyl and iso-propyl), butyl (e.g., n-butyl,iso-butyl, sec-butyl, tert-butyl), pentyl groups (e.g., n-pentyl,iso-pentyl, neopentyl), hexyl groups, and the like. In variousembodiments, an alkyl group can have 1 to 40 carbon atoms (i.e., C₁₋₄₀alkyl group), for example, 1-20 carbon atoms (i.e., C₁₋₂₀ alkyl group).In some embodiments, an alkyl group can have 1 to 6 carbon atoms, andcan be referred to as a “lower alkyl group.” Examples of lower alkylgroups include methyl, ethyl, propyl (e.g., n-propyl and iso-propyl),and butyl groups (e.g., n-butyl, iso-butyl, sec-butyl, tert-butyl). Insome embodiments, alkyl groups can be substituted as described herein.An alkyl group is generally not substituted with another alkyl group, analkenyl group, or an alkynyl group.

As used herein, “haloalkyl” refers to an alkyl group having one or morehalogen substituents. At various embodiments, a haloalkyl group can have1 to 40 carbon atoms (i.e., C₁₋₄₀ haloalkyl group), for example, 1 to 20carbon atoms (i.e., C₁₋₂₀ haloalkyl group). Examples of haloalkyl groupsinclude CF₃, C₂F₅, CHF₂, CH₂F, CCl₃, CHCl₂, CH₂Cl, C₂Cl₅, and the like.Perhaloalkyl groups, i.e., alkyl groups where all of the hydrogen atomsare replaced with halogen atoms (e.g., CF₃ and C₂F₅), are includedwithin the definition of “haloalkyl.” For example, a C₁₋₄₀ haloalkylgroup can have the formula —C_(s)H_(2s+1−t)X⁰ _(t), where X⁰, at eachoccurrence, is F, Cl, Br or I, s is an integer in the range of 1 to 40,and t is an integer in the range of 1 to 81, provided that t is lessthan or equal to 2s+1. Haloalkyl groups that are not perhaloalkyl groupscan be substituted as described herein.

As used herein, “alkoxy” refers to —O-alkyl group. Examples of alkoxygroups include, but are not limited to, methoxy, ethoxy, propoxy (e.g.,n-propoxy and isopropoxy), t-butoxy, pentoxy, hexoxy groups, and thelike. The alkyl group in the —O-alkyl group can be substituted asdescribed herein. For example, an —O-haloalkyl group is consideredwithin the definition of “alkoxy” as used herein.

As used herein, “alkylthio” refers to an —S-alkyl group (which, in somecases, can be expressed as —S(O)_(w)-alkyl, wherein w is 0). Examples ofalkylthio groups include, but are not limited to, methylthio, ethylthio,propylthio (e.g., n-propylthio and isopropylthio), t-butylthio,pentylthio, hexylthio groups, and the like. The alkyl group in the—S-alkyl group can be substituted as described herein.

As used herein, “arylalkyl” refers to an -alkyl-aryl group, where thearylalkyl group is covalently linked to the defined chemical structurevia the alkyl group. An arylalkyl group is within the definition of a—Y—C₆₋₁₄ aryl group, where Y is defined as a divalent alky group thatcan be optionally substituted as described herein. An example of anarylalkyl group is a benzyl group (—CH₂—C₆H₅). An arylalkyl group can beoptionally substituted, i.e., the aryl group and/or the alkyl group, canbe substituted as disclosed herein.

As used herein, “alkenyl” refers to a straight-chain or branched alkylgroup having one or more carbon-carbon double bonds. Examples of alkenylgroups include ethenyl, propenyl, butenyl, pentenyl, hexenyl,butadienyl, pentadienyl, hexadienyl groups, and the like. The one ormore carbon-carbon double bonds can be internal (such as in 2-butene) orterminal (such as in 1-butene). In various embodiments, an alkenyl groupcan have 2 to 40 carbon atoms (i.e., C₂₋₄₀ alkenyl group), for example,2 to 20 carbon atoms (i.e., C₂₋₂₀ alkenyl group). In some embodiments,alkenyl groups can be substituted as described herein. An alkenyl groupis generally not substituted with another alkenyl group, an alkyl group,or an alkynyl group.

As used herein, “alkynyl” refers to a straight-chain or branched alkylgroup having one or more triple carbon-carbon bonds. Examples of alkynylgroups include ethynyl, propynyl, butynyl, pentynyl, hexynyl, and thelike. The one or more triple carbon-carbon bonds can be internal (suchas in 2-butyne) or terminal (such as in 1-butyne). In variousembodiments, an alkynyl group can have 2 to 40 carbon atoms (i.e., C₂₋₄₀alkynyl group), for example, 2 to 20 carbon atoms (i.e., C₂₋₂₀ alkynylgroup). In some embodiments, alkynyl groups can be substituted asdescribed herein. An alkynyl group is generally not substituted withanother alkynyl group, an alkyl group, or an alkenyl group.

As used herein, “cycloalkyl” refers to a non-aromatic carbocyclic groupincluding cyclized alkyl, alkenyl, and alkynyl groups. In variousembodiments, a cycloalkyl group can have 3 to 24 carbon atoms, forexample, 3 to 20 carbon atoms (e.g., C₃₋₁₄ cycloalkyl group). Acycloalkyl group can be monocyclic (e.g., cyclohexyl) or polycyclic(e.g., containing fused, bridged, and/or spiro ring systems), where thecarbon atoms are located inside or outside of the ring system. Anysuitable ring position of the cycloalkyl group can be covalently linkedto the defined chemical structure. Examples of cycloalkyl groups includecyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl,cyclopentenyl, cyclohexenyl, cyclohexadienyl, cycloheptatrienyl,norbornyl, norpinyl, norcaryl, adamantyl, and spiro[4.5]decanyl groups,as well as their homologs, isomers, and the like. In some embodiments,cycloalkyl groups can be substituted as described herein.

As used herein, “heteroatom” refers to an atom of any element other thancarbon or hydrogen and includes, for example, nitrogen, oxygen, silicon,sulfur, phosphorus, and selenium.

As used herein, “cycloheteroalkyl” refers to a non-aromatic cycloalkylgroup that contains at least one ring heteroatom selected from O, S, Se,N, P, and Si (e.g., O, S, and N), and optionally contains one or moredouble or triple bonds. A cycloheteroalkyl group can have 3 to 24 ringatoms, for example, 3 to 20 ring atoms (e.g., 3-14 memberedcycloheteroalkyl group). One or more N, P, S, or Se atoms (e.g., N or S)in a cycloheteroalkyl ring may be oxidized (e.g., morpholine N-oxide,thiomorpholine S-oxide, thiomorpholine S,S-dioxide). In someembodiments, nitrogen or phosphorus atoms of cycloheteroalkyl groups canbear a substituent, for example, a hydrogen atom, an alkyl group, orother substituents as described herein. Cycloheteroalkyl groups can alsocontain one or more oxo groups, such as oxopiperidyl, oxooxazolidyl,dioxo-(1H,3H)-pyrimidyl, oxo-2(1H)-pyridyl, and the like. Examples ofcycloheteroalkyl groups include, among others, morpholinyl,thiomorpholinyl, pyranyl, imidazolidinyl, imidazolinyl, oxazolidinyl,pyrazolidinyl, pyrazolinyl, pyrrolidinyl, pyrrolinyl, tetrahydrofuranyl,tetrahydrothiophenyl, piperidinyl, piperazinyl, and the like. In someembodiments, cycloheteroalkyl groups can be substituted as describedherein.

As used herein, “aryl” refers to an aromatic monocyclic hydrocarbon ringsystem or a polycyclic ring system in which two or more aromatichydrocarbon rings are fused (i.e., having a bond in common with)together or at least one aromatic monocyclic hydrocarbon ring is fusedto one or more cycloalkyl and/or cycloheteroalkyl rings. An aryl groupcan have 6 to 24 carbon atoms in its ring system (e.g., C₆₋₂₀ arylgroup), which can include multiple fused rings. In some embodiments, apolycyclic aryl group can have 8 to 24 carbon atoms. Any suitable ringposition of the aryl group can be covalently linked to the definedchemical structure. Examples of aryl groups having only aromaticcarbocyclic ring(s) include phenyl, 1-naphthyl (bicyclic), 2-naphthyl(bicyclic), anthracenyl (tricyclic), phenanthrenyl (tricyclic),pentacenyl (pentacyclic), and like groups. Examples of polycyclic ringsystems in which at least one aromatic carbocyclic ring is fused to oneor more cycloalkyl and/or cycloheteroalkyl rings include, among others,benzo derivatives of cyclopentane (i.e., an indanyl group, which is a5,6-bicyclic cycloalkyl/aromatic ring system), cyclohexane (i.e., atetrahydronaphthyl group, which is a 6,6-bicyclic cycloalkyl/aromaticring system), imidazoline (i.e., a benzimidazolinyl group, which is a5,6-bicyclic cycloheteroalkyl/aromatic ring system), and pyran (i.e., achromenyl group, which is a 6,6-bicyclic cycloheteroalkyl/aromatic ringsystem). Other examples of aryl groups include benzodioxanyl,benzodioxolyl, chromanyl, indolinyl groups, and the like. In someembodiments, aryl groups can be substituted as described herein. In someembodiments, an aryl group can have one or more halogen substituents,and can be referred to as a “haloaryl” group. Perhaloaryl groups, i.e.,aryl groups where all of the hydrogen atoms are replaced with halogenatoms (e.g., —C₆F₅), are included within the definition of“haloaryl.” Incertain embodiments, an aryl group is substituted with another arylgroup and can be referred to as a biaryl group. Each of the aryl groupsin the biaryl group can be substituted as disclosed herein.

As used herein, “heteroaryl” refers to an aromatic monocyclic ringsystem containing at least one ring heteroatom selected from oxygen (O),nitrogen (N), sulfur (S), silicon (Si), and selenium (Se) or apolycyclic ring system where at least one of the rings present in thering system is aromatic and contains at least one ring heteroatom.Polycyclic heteroaryl groups include those having two or more heteroarylrings fused together, as well as those having at least one monocyclicheteroaryl ring fused to one or more aromatic carbocyclic rings,non-aromatic carbocyclic rings, and/or non-aromatic cycloheteroalkylrings. A heteroaryl group, as a whole, can have, for example, 5 to 24ring atoms and contain 1-5 ring heteroatoms (i.e., 5-20 memberedheteroaryl group). The heteroaryl group can be attached to the definedchemical structure at any heteroatom or carbon atom that results in astable structure. Generally, heteroaryl rings do not contain O—O, S—S,or S—O bonds. However, one or more N or S atoms in a heteroaryl groupcan be oxidized (e.g., pyridine N-oxide, thiophene S-oxide, thiopheneS,S-dioxide). Examples of heteroaryl groups include, for example, the 5-or 6-membered monocyclic and 5-6 bicyclic ring systems shown below:

where T is O, S, NH, N-alkyl, N-aryl, N-(arylalkyl) (e.g., N-benzyl),SiH₂, SiH(alkyl), Si(alkyl)₂, SiH(arylalkyl), Si(arylalkyl)₂, orSi(alkyl)(arylalkyl). Examples of such heteroaryl rings includepyrrolyl, furyl, thienyl, pyridyl, pyrimidyl, pyridazinyl, pyrazinyl,triazolyl, tetrazolyl, pyrazolyl, imidazolyl, isothiazolyl, thiazolyl,thiadiazolyl, isoxazolyl, oxazolyl, oxadiazolyl, indolyl, isoindolyl,benzofuryl, benzothienyl, quinolyl, 2-methylquinolyl, isoquinolyl,quinoxalyl, quinazolyl, benzotriazolyl, benzimidazolyl, benzothiazolyl,benzisothiazolyl, benzisoxazolyl, benzoxadiazolyl, benzoxazolyl,cinnolinyl, 1H-indazolyl, 2H-indazolyl, indolizinyl, isobenzofuyl,naphthyridinyl, phthalazinyl, pteridinyl, purinyl, oxazolopyridinyl,thiazolopyridinyl, imidazopyridinyl, furopyridinyl, thienopyridinyl,pyridopyrimidinyl, pyridopyrazinyl, pyridopyridazinyl, thienothiazolyl,thienoxazolyl, thienoimidazolyl groups, and the like. Further examplesof heteroaryl groups include 4,5,6,7-tetrahydroindolyl,tetrahydroquinolinyl, benzothienopyridinyl, benzofuropyridinyl groups,and the like. In some embodiments, heteroaryl groups can be substitutedas described herein.

Compounds of the present teachings can include a “divalent group”defined herein as a linking group capable of forming a covalent bondwith two other moieties. For example, compounds of the present teachingscan include a divalent C₁₋₂₀ alkyl group (e.g., a methylene group), adivalent C₂₋₂₀ alkenyl group (e.g., a vinylyl group), a divalent C₂₋₂₀alkynyl group (e.g., an ethynylyl group). a divalent C₆₋₁₄ aryl group(e.g., a phenylyl group); a divalent 3-14 membered cycloheteroalkylgroup (e.g., a pyrrolidylyl), and/or a divalent 5-14 membered heteroarylgroup (e.g., a thienylyl group). Generally, a chemical group (e.g.,—Ar—) is understood to be divalent by the inclusion of the two bondsbefore and after the group.

The electron-donating or electron-withdrawing properties of severalhundred of the most common substituents, reflecting all common classesof substituents have been determined, quantified, and published. Themost common quantification of electron-donating and electron-withdrawingproperties is in terms of Hammett a values. Hydrogen has a Hammett avalue of zero, while other substituents have Hammett a values thatincrease positively or negatively in direct relation to theirelectron-withdrawing or electron-donating characteristics. Substituentswith negative Hammett a values are considered electron-donating, whilethose with positive Hammett a values are consideredelectron-withdrawing. See Lange's Handbook of Chemistry, 12th ed.,McGraw Hill, 1979, Table 3-12, pp. 3-134 to 3-138, which lists Hammett avalues for a large number of commonly encountered substituents and isincorporated by reference herein.

It should be understood that the term “electron-accepting group” can beused synonymously herein with “electron acceptor” and“electron-withdrawing group”. In particular, an “electron-withdrawinggroup” (“EWG”) or an “electron-accepting group” or an“electron-acceptor” refers to a functional group that draws electrons toitself more than a hydrogen atom would if it occupied the same positionin a molecule. Examples of electron-withdrawing groups include, but arenot limited to, halogen or halo (e.g., F, Cl, Br, I), —NO₂, —CN, —NC,—S(R⁰)₂ ⁺, —N(R⁰)₃ ⁺, —SO₃H, —SO₂R⁰, —SO₃R⁰, —SO₂NHR⁰, —SO₂N(R⁰)₂,—COOH, —COR⁰, —COOR⁰, —CONHR⁰, —CON(R⁰)₂, C₁₋₄₀ haloalkyl groups, C₆₋₁₄aryl groups, and 5-14 membered electron-poor heteroaryl groups; where R⁰is a C₁₋₂₀ alkyl group, a C₂₋₂₀ alkenyl group, a C₂₋₂₀ alkynyl group, aC₁₋₂₀ haloalkyl group, a C₁₋₂₀ alkoxy group, a C₆₋₁₄ aryl group, a C₃₋₁₄cycloalkyl group, a 3-14 membered cycloheteroalkyl group, and a 5-14membered heteroaryl group, each of which can be optionally substitutedas described herein. For example, each of the C₁₋₂₀ alkyl group, theC₂₋₂₀ alkenyl group, the C₂₋₂₀ alkynyl group, the C₁₋₂₀ haloalkyl group,the C₁₋₂₀ alkoxy group, the C₆₋₁₄ aryl group, the C₃₋₁₄ cycloalkylgroup, the 3-14 membered cycloheteroalkyl group, and the 5-14 memberedheteroaryl group can be optionally substituted with 1-5 smallelectron-withdrawing groups such as F, Cl, Br, —NO₂, —CN, —NC, —S(R⁰)₂⁺, —N(R⁰)₃ ⁺, —SO₃H, —SO₂R⁰, —SO₃R⁰, —SO₂NHR⁰, —SO₂N(R⁰)₂, —COOH, —COR⁰,—COOR⁰, —CONHR⁰, and —CON(R⁰)₂.

It should be understood that the term “electron-donating group” can beused synonymously herein with “electron donor”. In particular, an“electron-donating group” or an “electron-donor” refers to a functionalgroup that donates electrons to a neighboring atom more than a hydrogenatom would if it occupied the same position in a molecule. Examples ofelectron-donating groups include —OH, —OR⁰, —NH₂, —NHR⁰, —N(R⁰)₂, and5-14 membered electron-rich heteroaryl groups, where R⁰ is a C₁₋₂₀ alkylgroup, a C₂₋₂₀ alkenyl group, a C₂₋₂₀ alkynyl group, a C₆₋₁₄ aryl group,or a C₃₋₁₄ cycloalkyl group.

Various unsubstituted heteroaryl groups can be described aselectron-rich (or π-excessive) or electron-poor (or π-deficient). Suchclassification is based on the average electron density on each ringatom as compared to that of a carbon atom in benzene. Examples ofelectron-rich systems include 5-membered heteroaryl groups having oneheteroatom such as furan, pyrrole, and thiophene; and their benzofusedcounterparts such as benzofuran, benzopyrrole, and benzothiophene.Examples of electron-poor systems include 6-membered heteroaryl groupshaving one or more heteroatoms such as pyridine, pyrazine, pyridazine,and pyrimidine; as well as their benzofused counterparts such asquinoline, isoquinoline, quinoxaline, cinnoline, phthalazine,naphthyridine, quinazoline, phenanthridine, acridine, and purine. Mixedheteroaromatic rings can belong to either class depending on the type,number, and position of the one or more heteroatom(s) in the ring. SeeKatritzky, A. R and Lagowski, J. M., Heterocyclic Chemistry (John Wiley& Sons, New York, 1960).

At various places in the present specification, substituents aredisclosed in groups or in ranges. It is specifically intended that thedescription include each and every individual subcombination of themembers of such groups and ranges. For example, the term “C₁₋₆ alkyl” isspecifically intended to individually disclose C₁, C₂, C₃, C₄, C₅, C₆,C₁-C₆, C₁-C₅, C₁-C₄, C₁-C₃, C₁-C₂, C₂-C₆, C₂-C₅, C₂-C₄, C₂-C₃, C₃-C₆,C₃- C₅, C₃-C₄, C₄-C₆, C₄-C₅, and C₅-C₆ alkyl. By way of other examples,an integer in the range of 0 to 40 is specifically intended toindividually disclose 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32,33, 34, 35, 36, 37, 38, 39, and 40, and an integer in the range of 1 to20 is specifically intended to individually disclose 1, 2, 3, 4, 5, 6,7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20. Additionalexamples include that the phrase “optionally substituted with 1-5substituents” is specifically intended to individually disclose achemical group that can include 0, 1, 2, 3, 4, 5, 0-5, 0-4, 0-3, 0-2,0-1, 1-5, 1-4, 1-3, 1-2, 2-5, 2-4, 2-3, 3-5, 3-4, and 4-5 substituents.

Compounds described herein can contain an asymmetric atom (also referredas a chiral center) and some of the compounds can contain two or moreasymmetric atoms or centers, which can thus give rise to optical isomers(enantiomers) and diastereomers (geometric isomers). The presentteachings include such optical isomers and diastereomers, includingtheir respective resolved enantiomerically or diastereomerically pureisomers (e.g., (+) or (−) stereoisomer) and their racemic mixtures, aswell as other mixtures of the enantiomers and diastereomers. In someembodiments, optical isomers can be obtained in enantiomericallyenriched or pure form by standard procedures known to those skilled inthe art, which include, for example, chiral separation, diastereomericsalt formation, kinetic resolution, and asymmetric synthesis. Thepresent teachings also encompass cis- and trans-isomers of compoundscontaining alkenyl moieties (e.g., alkenes, azo, and imines). It alsoshould be understood that the compounds of the present teachingsencompass all possible regioisomers in pure form and mixtures thereof.In some embodiments, the preparation of the present compounds caninclude separating such isomers using standard separation proceduresknown to those skilled in the art, for example, by using one or more ofcolumn chromatography, thin-layer chromatography, simulated moving-bedchromatography, and high-performance liquid chromatography. However,mixtures of regioisomers can be used similarly to the uses of eachindividual regioisomer of the present teachings as described hereinand/or known by a skilled artisan.

It is specifically contemplated that the depiction of one regioisomerincludes any other regioisomers and any regioisomeric mixtures unlessspecifically stated otherwise.

As used herein, a “leaving group” (“LG”) refers to a charged oruncharged atom (or group of atoms) that can be displaced as a stablespecies as a result of, for example, a substitution or eliminationreaction. Examples of leaving groups include, but are not limited to,halogen (e.g., Cl, Br, I), azide (N₃), thiocyanate (SCN), nitro (NO₂),cyanate (CN), water (H₂O), ammonia (NH₃), and sulfonate groups (e.g.,OSO₂—R, wherein R can be a C₁₋₁₀ alkyl group or a C₆₋₁₄ aryl group eachoptionally substituted with 1-4 groups independently selected from aC₁₋₁₀ alkyl group and an electron-withdrawing group) such as tosylate(toluenesulfonate, OTs), mesylate (methanesulfonate, OMs), brosylate(p-bromobenzenesulfonate, OBs), nosylate (4-nitrobenzenesulfonate, ONs),and triflate (trifluoromethanesulfonate, OTf).

As used herein, a “p-type semiconductor material” or a “p-typesemiconductor” refers to a semiconductor material having holes as themajority current or charge carriers. In some embodiments, when a p-typesemiconductor material is deposited on a substrate, it can provide ahole mobility in excess of about 10⁻⁵ cm²/Vs. In the case offield-effect devices, a p-type semiconductor can also exhibit a currenton/off ratio of greater than about 10.

As used herein, an “n-type semiconductor material” or an “n-typesemiconductor” refers to a semiconductor material having electrons asthe majority current or charge carriers. In some embodiments, when ann-type semiconductor material is deposited on a substrate, it canprovide an electron mobility in excess of about 10⁻⁵ cm²/Vs. In the caseof field-effect devices, an n-type semiconductor can also exhibit acurrent on/off ratio of greater than about 10.

As used herein, “mobility” refers to a measure of the velocity withwhich charge carriers, for example, holes (or units of positive charge)in the case of a p-type semiconductor material and electrons in the caseof an n-type semiconductor material, move through the material under theinfluence of an electric field. This parameter, which depends on thedevice architecture, can be measured using a field-effect device orspace-charge limited current measurements.

As used herein, fill factor (FF) is the ratio (given as a percentage) ofthe actual maximum obtainable power, (P_(m) or V_(mp)*J_(mp)), to thetheoretical (not actually obtainable) power, (J_(sc)×V_(oc)).Accordingly, FF can be determined using the equation:

FF=(V _(mp) *J _(mp))/(J _(sc) *V _(oc))

where J_(mp) and V_(mp) represent the current density and voltage at themaximum power point (P_(m)), respectively, this point being obtained byvarying the resistance in the circuit until J*V is at its greatestvalue; and J_(sc) and V_(oc) represent the short circuit current and theopen circuit voltage, respectively. Fill factor is a key parameter inevaluating the performance of solar cells. Commercial solar cellstypically have a fill factor of about 0.60% or greater.

As used herein, the open-circuit voltage (V_(oc)) is the difference inthe electrical potentials between the anode and the cathode of a devicewhen there is no external load connected.

As used herein, the power conversion efficiency (PCE) of a solar cell isthe percentage of power converted from absorbed light to electricalenergy. The PCE of a solar cell can be calculated by dividing themaximum power point (P_(m)) by the input light irradiance (E, in W/m²)under standard test conditions (STC) and the surface area of the solarcell (A° in m²). STC typically refers to a temperature of 25° C. and anirradiance of 1000 W/m² with an air mass 1.5 (AM 1.5) spectrum.

As used herein, a component (such as a thin film layer) can beconsidered “photoactive” if it contains one or more compounds that canabsorb photons to produce excitons for the generation of a photocurrent.

Throughout the specification, structures may or may not be presentedwith chemical names. Where any question arises as to nomenclature, thestructure prevails.

In one aspect, the present teachings relate to polymeric semiconductingcompounds, as well as the use of these compounds in electronic,optoelectronic, or optical devices. The polymeric compounds (orpolymers) according to the present teachings generally can berepresented by formula (I):

wherein:R¹ and R² independently are a C₁₋₂₀ alkyl group or a C₁₋₂₀ haloalkylgroup;Ar¹ and Ar² independently are an optionally substituted C₆₋₁₄ aryl groupor an optionally substituted 5-14 membered heteroaryl group;π is an optionally substituted polycyclic aryl or heteroaryl group;m¹ and m² independently are 0, 1, 2, 3 or 4;p is 0 or 1;x and y are real numbers representing mole fractions, wherein 0<x≦1,0≦y<1, and the sum of x and y is about 1; andthe polymeric compound has a degree of polymerization (n) in the rangeof 5 to 10,000.

To illustrate, each of R¹ and R² independently can be a linear orbranched C₁₋₄₀ alkyl groups such as methyl, ethyl, n-propyl, isopropyl,n-butyl, iso-butyl, sec-butyl, tert-butyl, n-pentyl, iso-pentyl,neo-pentyl, n-hexyl, n-dodecyl,

or a linear or branched C₁₋₄₀ haloalkyl groups where one or morehydrogen atoms in, for example, the C₁₋₄₀ alkyl groups shown above, arereplaced by a halogen such as F.

Examples of Ar¹ and Ar² include various conjugated monocyclic andpolycyclic moieties which can be optionally substituted as describedherein. For example, each of Ar¹ and Ar² optionally can be substitutedwith 1-6 R^(d) groups, where

-   -   R^(d), at each occurrence, independently is selected from a)        halogen, b) —CN, c) —NO₂, d) —N(R^(e))₂, e) oxo, f) —OH, g)        ═C(R^(f))₂, h) —C(O)R^(e), i) —C(O)OR^(e), j) —C(O)N(R^(e))₂, k)        —SH, l) —S(O)₂—R^(e), m) —S(O)₂OR^(e), n)        —(OCH₂CH₂)_(t)OR^(e), o) —(OCF₂CF₂)_(t)OR^(e), p)        —(OCH₂CF₂)_(t)OR^(e), q) —(OCF₂CH₂)_(t)OR^(e), r)        —(CH₂CH₂O)_(t)R^(e), s) —(CF₂CF₂O)_(t)R^(e), t)        —(CH₂CF₂O)_(t)R^(e), u) —(CF₂CH₂O)_(t)R^(e), v) a C₁₋₄₀ alkyl        group, w) a C₂₋₄₀ alkenyl group, x) a C₂₋₄₀ alkynyl group, y) a        C₁₋₄₀ alkoxy group, z) a C₁₋₄₀ alkylthio group, aa) a C₁₋₄₀        haloalkyl group, ab) a —Y—C₃₋₁₀ cycloalkyl group, ac) a —Y—C₆₋₁₄        aryl group, ad) a —Y—C₆₋₁₄ haloaryl group, ae) a —Y-3-12        membered cycloheteroalkyl group, and af) a —Y-5-14 membered        heteroaryl group, wherein each of the C₁₋₄₀ alkyl group, the        C₂₋₄₀ alkenyl group, the C₂₋₄₀ alkynyl group, the C₁₋₄₀ alkoxy        group, the C₁₋₄₀ alkylthio group, the C₁₋₄₀ haloalkyl group, the        C₃₋₁₀ cycloalkyl group, the C₆₋₁₄ aryl group, the C₆₋₁₄ haloaryl        group, the 3-12 membered cycloheteroalkyl group, and the 5-14        membered heteroaryl group is optionally substituted with 1-4        R^(f) groups;    -   R^(e), at each occurrence, independently is selected from H, a        C₁₋₄₀ alkyl group, a C₁₋₄₀ haloalkyl group, and a —Y—C₆₋₁₄ aryl        group;    -   R^(f), at each occurrence, independently is selected from a)        halogen, b) —CN, c) —NO₂, d) oxo, e) —OH, f) —NH₂, g) —NH(C₁₋₂₀        alkyl), h) —N(C₁₋₂₀ alkyl)₂, i) —N(C₁₋₂₀ alkyl)-C₆₋₁₄ aryl, j)        —N(C₆₋₁₄ aryl)₂, k) —S(O)_(w)H, l) —S(O)_(w)—C₁₋₂₀ alkyl, m)        —S(O)₂OH, n) —S(O)₂—OC₁₋₂₀ alkyl, o) —S(O)₂—OC₆₋₁₄ aryl, p)        —CHO, q) —C(O)—C₁₋₂₀ alkyl, r) —C(O)—C₆₋₁₄ aryl, s) —C(O)OH, t)        —C(O)—OC₁₋₂₀ alkyl, u) —C(O)—OC₆₋₁₄ aryl, v) —C(O)NH₂, w)        —C(O)NH—C₁₋₂₀ alkyl, x) —C(O)N(C₁₋₂₀ alkyl)₂, y) —C(O)NH—C₆₋₁₄        aryl, z) —C(O)N(C₁₋₂₀ alkyl)-C₆₋₁₄ aryl, aa) —C(O)N(C₆₋₁₄        aryl)₂, ab) —C(S)NH₂, ac) —C(S)NH—C₁₋₂₀ alkyl, ad) —C(S)N(C₁₋₂₀        alkyl)₂, ae) —C(S)N(C₆₋₁₄ aryl)₂, af) —C(S)N(C₁₋₂₀ alkyl)-C₆₋₁₄        aryl, ag) —C(S)NH—C₆₋₁₄ aryl, ah) —S(O)_(w)NH₂, ai)        —S(O)_(w)NH(C₁₋₂₀ alkyl), aj) —S(O)_(w)N(C₁₋₂₀ alkyl)₂, ak)        —S(O)_(w)NH(C₆₋₁₄ aryl), al) —S(O)_(w)N(C₁₋₂₀ alkyl)-C₆₋₁₄ aryl,        am) —S(O)_(w)N(C₆₋₁₄ aryl)₂, an) —SiH₃, ao) —SiH(C₁₋₂₀ alkyl)₂,        ap) —SiH₂(C₁₋₂₀ alkyl), aq) —Si(C₁₋₂₀ alkyl)₃, ar) a C₁₋₂₀ alkyl        group, as) a C₂₋₂₀ alkenyl group, at) a C₂₋₂₀ alkynyl group, au)        a C₁₋₂₀ alkoxy group, av) a C₁₋₂₀ alkylthio group, aw) a C₁₋₂₀        haloalkyl group, ax) a C₃₋₁₀ cycloalkyl group, ay) a C₆₋₁₄ aryl        group, az) a C₆₋₁₄ haloaryl group, ba) a 3-12 membered        cycloheteroalkyl group, or bb) a 5-14 membered heteroaryl group;    -   Y, at each occurrence, independently is selected from a divalent        C₁₋₁₀ alkyl group, a divalent C₁₋₁₀ haloalkyl group, and a        covalent bond;    -   t is 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10; and    -   w, at each occurrence, independently is 0, 1, or 2.

Examples of monocyclic (hetero)aryl groups include a phenyl group or a5- or 6-membered heteroaryl group such as a pyrrolyl group, a furylgroup, a thienyl group, a pyridyl group, a pyrimidyl group, apyridazinyl group, a pyrazinyl group, a triazolyl group, a tetrazolylgroup, a pyrazolyl group, an imidazolyl group, an isothiazolyl group, athiazolyl group, and a thiadiazolyl group. For example, at least one ofthe Ar¹ and/or the Ar² groups can include at least one 5-memberedheteroaryl group that includes at least one sulfur ring atom. Examplesof such sulfur-containing 5-membered heteroaryl group include a thienylgroup, a thiazolyl group, an isothiazolyl group, and a thiadiazolylgroup, each of which optionally can be substituted with 1-4 R³ groups,where R³, at each occurrence, independently can be selected from ahalogen, CN, oxo, ═C(CN)₂, a C₁₋₄₀ alkyl group, a C₁₋₄₀ haloalkyl group,a C₁₋₄₀ alkoxy group, and a C₁₋₄₀ alkylthio group.

Examples of bicyclic 8-14 membered (hetero)aryl groups include anaphthyl group and various bicyclic (e.g., 5-5 or 5-6) heteroarylmoieties that include at least one sulfur ring atom. Examples of suchsulfur-containing bicyclic heteroaryl moieties include athienothiophenyl group (e.g., a thieno[3,2-b]thiophenyl group or athieno[2,3-b]thiophenyl group), a benzothienyl group, a benzothiazolylgroup, a benzisothiazolyl group, and a benzothiadiazolyl group, each ofwhich optionally can be substituted with 1-4 R³ groups, where R³, ateach occurrence, independently can be selected from a halogen, CN, oxo,═C(CN)₂, a C-40 alkyl group, a C₁₋₄₀ haloalkyl group, a C₁₋₄₀ alkoxygroup, and a C₁₋₄₀ alkylthio group.

By way of example, Ar¹ and Ar², at each occurrence, independently can beselected from:

where R⁴, at each occurrence, independently can be H or R³, and R³ canbe selected from a halogen, CN, oxo, ═C(CN)₂, a C₁₋₄₀ alkyl group, aC₁₋₄₀ haloalkyl group, a C₁₋₄₀ alkoxy group, and a C₁₋₄₀ alkylthiogroup.

In various embodiments, at least p and/or at least one of m¹ and m² isnot 0. For example, in certain embodiments, each of m¹ and m² can be 1,and Ar¹ and Ar², at each occurrence, independently can be an optionallysubstituted thienyl group or an optionally substituted bicyclicheteroaryl group comprising a thienyl group fused with a 5-memberedheteroaryl group. In particular embodiments, the present polymers canhave the formula:

wherein:R³, R⁴, R⁵, and R⁶ independently are selected from H and R⁷, wherein R⁷,at each occurrence, independently is selected from a halogen, CN, aC₁₋₂₀ alkyl group, a C₁₋₂₀ haloalkyl group, a C₁₋₂₀ alkoxy group, and aC₁₋₂₀ alkylthio group; andR¹, R², π, p, x and y are as defined herein.

In certain embodiments, p can be 0. An example of such embodiments canbe a polymer having the formula:

where R¹ and R² independently can be a C₁₋₂₀ alkyl group; and n is aninteger ranging from 5 to 10,000. Another example of such embodimentscan be a polymer having the formula:

where R¹ and R² independently can be a C₁₋₂₀ alkyl group, where each R⁷is selected from a halogen, CN, a C₁₋₂₀ alkyl group, a C₁₋₂₀ haloalkylgroup, a C₁₋₂₀ alkoxy group, and a C₁₋₂₀ alkylthio group; and n is aninteger ranging from 5 to 10,000.

In certain embodiments, p can be 1. Examples of such embodiments caninclude polymers having the formula:

wherein π is an optionally substituted heteroaryl group. For example, πcan be a polycyclic C₈₋₂₄ aryl group or a polycyclic 8-24 memberedheteroaryl group, where each of these groups can be optionallysubstituted with 1-6 R^(d) groups, where R^(d) is as defined herein. Incertain embodiments, π can include at least one electron-withdrawinggroup. In certain embodiments, π can include one or more solubilizinggroups. For example, π can include one or more solubilizing groupsselected from a C₁₋₄₀ alkyl group, a C₁₋₄₀ alkoxy group, a C₁₋₄₀alkylthio group, a C₁₋₄₀ haloalkyl group, —(OCH₂CH₂)_(t)OR^(e),—(OCF₂CF₂)_(t)OR^(e), —(OCH₂CF₂)_(t)OR^(e), —(OCF₂CH₂)_(t)OR^(e),—(CH₂CH₂O)_(t)—R^(e), —(CF₂CF₂O)_(t)R^(e), —(CH₂CF₂O)_(t)R^(e), or—(CF₂CH₂O)_(t)Re; where t is 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10; and R^(e)is a C₁₋₂₀ alkyl group or a C₁₋₂₀ haloalkyl group.

In certain embodiments, π can be an optionally substituted heteroarylgroup represented by a formula selected from:

wherein Het, at each occurrence, is a monocyclic moiety including atleast one heteroatom in its ring and optionally substituted with 1-2 R¹⁰groups, wherein R⁸, R⁹, and R¹⁰ independently can be H or R⁷, whereinR⁷, at each occurrence, independently is selected from a halogen, CN, aC₁₋₂₀ alkyl group, a C₁₋₂₀ haloalkyl group, a C₁₋₂₀ alkoxy group, and aC₁₋₂₀ alkylthio group; and R¹, R², x and y are as defined herein.

In particular embodiments, π can be selected from:

where R⁸, R⁹, and R¹⁰ independently can be selected from H, halogen, CN,a C₁₋₂₀ alkyl group, a C₁₋₂₀ haloalkyl group, a C₁₋₂₀ alkoxy group, anda C₁₋₂₀ alkylthio group.

To illustrate, an example of a polymer having the formula:

where R¹, R² and R¹⁰ independently can be a C₁₋₂₀ alkyl group, and n isan integer ranging from 5 to 10,000.

In some embodiments, polymers according to the present teachings canhave the formula:

wherein π is as defined herein. For example, π can be an optionallysubstituted heteroaryl group represented by a formula selected from:

wherein Het, at each occurrence, is a monocyclic moiety including atleast one heteroatom in its ring and optionally substituted with 1-2 R¹⁰groups, wherein R⁸, R⁹, and R¹⁰ independently can be H or R⁷, whereinR⁷, at each occurrence, independently is selected from a halogen, CN, aC₁₋₂₀ alkyl group, a C₁₋₂₀ haloalkyl group, a C₁₋₂₀ alkoxy group, and aC₁₋₂₀ alkylthio group; and R¹, R², x and y are as defined herein.

To illustrate, an example of such embodiments can be a polymer havingthe formula:

wherein R¹, R² and R¹⁰ independently are a C₁₋₂₀ alkyl group, and n isan integer ranging from 5 to 10,000.

In one aspect, the present teachings relate to molecular semiconductingcompounds, as well as the use of these compounds in electronic,optoelectronic, or optical devices. These molecular compounds can berepresented by formula (II):

wherein:R¹ and R² independently are a C₁₋₂₀ alkyl group or a C₁₋₂₀ haloalkylgroup;Ar¹, Ar², Ar³, and Ar⁴ independently are an optionally substituted C₆₋₁₄aryl group or an optionally substituted 5-14 membered heteroaryl group;π, at each occurrence, independently is an optionally substitutedpolycyclic aryl or heteroaryl group;m¹, m², m³ and m⁴ independently are 1, 2, 3 or 4; andp is 0 or 1.

To illustrate, each of R¹ and R² independently can be a linear orbranched C₁₋₄₀ alkyl groups such as methyl, ethyl, n-propyl, isopropyl,n-butyl, iso-butyl, sec-butyl, tert-butyl, n-pentyl, iso-pentyl,neo-pentyl, n-hexyl, n-dodecyl,

or a linear or branched C₁₋₄₀ haloalkyl groups where one or morehydrogen atoms in, for example, the C₁₋₄₀ alkyl groups shown above, arereplaced by a halogen such as F.

Examples of Ar¹, Ar², Ar³, and Ar⁴ include various conjugated monocyclicand polycyclic moieties which can be optionally substituted as describedherein. For example, each of Ar¹, Ar², Ar³, and Ar⁴ optionally can besubstituted with 1-6 R^(d) groups, where

-   -   R^(d), at each occurrence, independently is selected from a)        halogen, b) —CN, c) —NO₂, d) —N(R^(e))₂, e) oxo, f) —OH, g)        ═C(R^(f))₂, h) —C(O)R^(e), i) —C(O)OR^(e), j) —C(O)N(R^(e))₂, k)        —SH, l) —S(O)₂R^(e), m) —S(O)₂OR^(e), n) (OCH₂CH₂)_(t)OR^(e), o)        —(OCF₂CF₂)_(t)OR^(e), p) (OCH₂CF₂)_(t)OR^(e), q)        —(OCF₂CH₂)_(t)OR^(e), r) (CH₂CH₂O)_(t)R^(e), s)        (CF₂CF₂O)_(t)R^(e), t) (CH₂CF₂O)_(t)R^(e), u)        (CF₂CH₂O)_(t)R^(e), v) a C₁₋₄₀ alkyl group, w) a C₂₋₄₀ alkenyl        group, x) a C₂₋₄₀ alkynyl group, y) a C₁₋₄₀ alkoxy group, z) a        C₁₋₄₀ alkylthio group, aa) a C₁₋₄₀ haloalkyl group, ab) a YC₃₋₁₀        cycloalkyl group, ac) a YC₆₋₁₄ aryl group, ad) a YC₆₋₁₄ haloaryl        group, ae) a Y-3-12 membered cycloheteroalkyl group, and af) a        Y-5-14 membered heteroaryl group, wherein each of the C₁₋₄₀        alkyl group, the C₂₋₄₀ alkenyl group, the C₂₋₄₀ alkynyl group,        the C₁₋₄₀ alkoxy group, the C₁₋₄₀ alkylthio group, the C₁₋₄₀        haloalkyl group, the C₃₋₁₀ cycloalkyl group, the C₆₋₁₄ aryl        group, the C₆₋₁₄ haloaryl group, the 3-12 membered        cycloheteroalkyl group, and the 5-14 membered heteroaryl group        is optionally substituted with 1-4 R^(f) groups;    -   R^(e), at each occurrence, independently is selected from H, a        C₁₋₄₀ alkyl group, a C₁₋₄₀ haloalkyl group, and a YC₆₋₁₄ aryl        group;    -   R^(f), at each occurrence, independently is selected from a)        halogen, b) —CN, c) —NO₂, d) oxo, e) —OH, f) —NH₂, g) —NH(C₁₋₂₀        alkyl), h) —N(C₁₋₂₀ alkyl)₂, i) —N(C₁₋₂₀ alkyl)-C₆₋₁₄ aryl, j)        —N(C₆₋₁₄ aryl)₂, k) —S(O)_(w)H, l) —S(O), C₁₋₂₀ alkyl, m)        —S(O)₂OH, n) —S(O)₂—OC₁₋₂₀ alkyl, o) —S(O)₂—OC₆₋₁₄ aryl, p)        —CHO, q) —C(O)C₁₋₂₀ alkyl, r) —C(O)C₆₋₁₄ aryl, s) —C(O)OH, t)        —C(O)—OC₁₋₂₀ alkyl, u) —C(O)—OC₆₋₁₄ aryl, v) —C(O)NH₂, w)        —C(O)NHC₁₋₂₀ alkyl, x) —C(O)N(C₁₋₂₀ alkyl)₂, y) —C(O)NHC₆₋₁₄        aryl, z) —C(O)N(C₁₋₂₀ alkyl)C₆₋₁₄ aryl, aa) —C(O)N(C₆₋₁₄ aryl)₂,        ab) —C(S)NH₂, ac) —C(S)NHC₁₋₂₀ alkyl, ad) —C(S)N(C₁₋₂₀ alkyl)₂,        ae) —C(S)N(C₆₋₁₄ aryl)₂, af) —C(S)N(C₁₋₂₀ alkyl)-C₆₋₁₄ aryl, ag)        —C(S)NH—C₆₋₁₄ aryl, ah) —S(O)_(w)NH₂, ai) —S(O)_(w)NH(C₁₋₂₀        alkyl), aj) —S(O)_(w)N(C₁₋₂₀ alkyl)₂, ak) —S(O)_(w)NH(C₆₋₁₄        aryl), al) —S(O)_(w)N(C₁₋₂₀ alkyl)-C₆₋₁₄ aryl, am)        —S(O)_(w)N(C₆₋₁₄ aryl)₂, an) —SiH₃, ao) —SiH(C₁₋₂₀ alkyl)₂, ap)        —SiH₂(C₁₋₂₀ alkyl), aq) —Si(C₁₋₂₀ alkyl)₃, ar) a C₁₋₂₀ alkyl        group, as) a C₂₋₂₀ alkenyl group, at) a C₂₋₂₀ alkynyl group, au)        a C₁₋₂₀ alkoxy group, av) a C₁₋₂₀ alkylthio group, aw) a C₁₋₂₀        haloalkyl group, ax) a C₃₋₁₀ cycloalkyl group, ay) a C₆₋₁₄ aryl        group, az) a C₆₋₁₄ haloaryl group, ba) a 3-12 membered        cycloheteroalkyl group, or bb) a 5-14 membered heteroaryl group;    -   Y, at each occurrence, independently is selected from a divalent        C₁₋₁₀ alkyl group, a divalent C₁₋₁₀ haloalkyl group, and a        covalent bond;    -   t is 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10; and    -   w, at each occurrence, independently is 0, 1, or 2.

Examples of monocyclic (hetero)aryl groups include a phenyl group or a5- or 6-membered heteroaryl group such as a pyrrolyl group, a furylgroup, a thienyl group, a pyridyl group, a pyrimidyl group, apyridazinyl group, a pyrazinyl group, a triazolyl group, a tetrazolylgroup, a pyrazolyl group, an imidazolyl group, an isothiazolyl group, athiazolyl group, and a thiadiazolyl group. For example, at least one ofAr¹, Ar², Ar³, and Ar⁴ can include at least one 5-membered heteroarylgroup that includes at least one sulfur ring atom. Examples of suchsulfur-containing 5-membered heteroaryl group include a thienyl group, athiazolyl group, an isothiazolyl group, and a thiadiazolyl group, eachof which optionally can be substituted with 1-4 R³ groups, where R³, ateach occurrence, independently can be selected from a halogen, CN, oxo,═C(CN)₂, a C₁₋₄₀ alkyl group, a C₁₋₄₀ haloalkyl group, a C₁₋₄₀ alkoxygroup, and a C₁₋₄₀ alkylthio group.

Examples of bicyclic 8-14 membered (hetero)aryl groups include anaphthyl group and various bicyclic (e.g., 5-5 or 5-6) heteroarylmoieties that include at least one sulfur ring atom. Examples of suchsulfur-containing bicyclic heteroaryl moieties include athienothiophenyl group (e.g., a thieno[3,2-b]thiophenyl group or athieno[2,3-b]thiophenyl group), a benzothienyl group, a benzothiazolylgroup, a benzisothiazolyl group, and a benzothiadiazolyl group, each ofwhich optionally can be substituted with 1-4 R³ groups, where R³, ateach occurrence, independently can be selected from a halogen, CN, oxo,═C(CN)₂, a C₁₋₄₀ alkyl group, a C₁₋₄₀ haloalkyl group, a C₁₋₄₀ alkoxygroup, and a C₁₋₄₀ alkylthio group.

By way of example, Ar¹, Ar², Ar³, and Ar⁴, at each occurrence,independently can be selected from:

where R⁴, at each occurrence, independently can be H or R³, and R³ canbe selected from a halogen, CN, oxo, ═C(CN)₂, a C₁₋₄₀ alkyl group, aC₁₋₄₀ haloalkyl group, a C₁₋₄₀ alkoxy group, and a C₁₋₄₀ alkylthiogroup.

In certain embodiments, Ar¹, Ar², Ar³, and Ar⁴, at each occurrence,independently can be an optionally substituted thienyl group or anoptionally substituted bicyclic heteroaryl group comprising a thienylgroup fused with a 5-membered heteroaryl group. In particularembodiments, a molecular semiconducting compound according to to thepresent teachings can have the formula:

wherein:

-   -   R³, R⁴, R⁵, and R⁶, at each occurrence, independently are        selected from H and R⁷, wherein R⁷, at each occurrence,        independently is selected from a halogen, CN, a C₁₋₂₀ alkyl        group, a C₁₋₂₀ haloalkyl group, a C₁₋₂₀ alkoxy group, and a        C₁₋₂₀ alkylthio group; and    -   R¹, R², π, and p are as defined herein.

In certain embodiments, p, at each occurrence, can be 1. In certainembodiments, π can be an optionally substituted heteroaryl grouprepresented by a formula selected from:

wherein Het, at each occurrence, is a monocyclic moiety including atleast one heteroatom in its ring and optionally substituted with 1-2 R¹⁰groups, wherein R⁸, R⁹, and R¹⁰ independently can be H or R⁷, whereinR⁷, at each occurrence, independently is selected from a halogen, CN, aC₁₋₂₀ alkyl group, a C₁₋₂₀ haloalkyl group, a C₁₋₂₀ alkoxy group, and aC₁₋₂₀ alkylthio group; and R¹, R², x and y are as defined herein. Inparticular embodiments, π can be selected from:

where R⁸, R⁹, and R¹⁰ independently can be selected from H, halogen, CN,a C₁₋₂₀ alkyl group, a C₁₋₂₀ haloalkyl group, a C₁₋₂₀ alkoxy group, anda C₁₋₂₀ alkylthio group.

To illustrate, a molecular semiconducting compound according to thepresent teachings can have the formula:

wherein R¹, R² and R¹⁰ independently can be a C₁₋₂₀ alkyl group.

Compounds of the present teachings can be prepared according toprocedures analogous to those described in the Examples. In particular,Stille coupling can be used to prepare polymeric compounds according tothe present teachings with high molecular weight and in high yield(>75%) and purity, as confirmed by ¹H NMR spectra, elemental analysis,and GPC measurements.

Alternatively, the present compounds can be prepared from commerciallyavailable starting materials, compounds known in the literature, or viaother readily prepared intermediates, by employing standard syntheticmethods and procedures known to those skilled in the art. Standardsynthetic methods and procedures for the preparation of organicmolecules and functional group transformations and manipulations can bereadily obtained from the relevant scientific literature or fromstandard textbooks in the field. It will be appreciated that wheretypical or preferred process conditions (i.e., reaction temperatures,times, mole ratios of reactants, solvents, pressures, etc.) are given,other process conditions can also be used unless otherwise stated.Optimum reaction conditions can vary with the particular reactants orsolvent used, but such conditions can be determined by one skilled inthe art by routine optimization procedures. Those skilled in the art oforganic synthesis will recognize that the nature and order of thesynthetic steps presented can be varied for the purpose of optimizingthe formation of the compounds described herein.

The processes described herein can be monitored according to anysuitable method known in the art. For example, product formation can bemonitored by spectroscopic means, such as nuclear magnetic resonancespectroscopy (NMR, e.g., ¹H or ¹³C), infrared spectroscopy (IR),spectrophotometry (e.g., UV-visible), mass spectrometry (MS), or bychromatography such as high pressure liquid chromatograpy (HPLC), gaschromatography (GC), gel-permeation chromatography (GPC), or thin layerchromatography (TLC).

The reactions or the processes described herein can be carried out insuitable solvents which can be readily selected by one skilled in theart of organic synthesis. Suitable solvents typically are substantiallynonreactive with the reactants, intermediates, and/or products at thetemperatures at which the reactions are carried out, i.e., temperaturesthat can range from the solvent's freezing temperature to the solvent'sboiling temperature. A given reaction can be carried out in one solventor a mixture of more than one solvent. Depending on the particularreaction step, suitable solvents for a particular reaction step can beselected.

Certain embodiments disclosed herein can be stable under ambientconditions (“ambient stable”), soluble in common solvents, and in turnsolution-processable into various articles, structures, or devices. Asused herein, a compound can be considered “ambient stable” or “stable atambient conditions” when the carrier mobility or the reduction-potentialof the compound is maintained at about its initial measurement when thecompound is exposed to ambient conditions, for example, air, ambienttemperature, and humidity, over a period of time. For example, a polymeraccording to the present teachings can be described as ambient stable ifits carrier mobility or reduction potential does not vary more than 20%or more than 10% from its initial value after exposure to ambientconditions, including, air, humidity and temperature, over a 3 day, 5day, or 10 day period. Without wishing to be bound by any particulartheory, it is believed that the strong electron-depleted electronicstructure of the thienocoronene moiety, and in the case of the polymers,the regioregular highly π-conjugated polymeric backbone, can make thepresent compounds ambient-stable n-channel semiconductor materialswithout requiring additional π-core functionalization (i.e., coresubstitution of the thienocoronene moiety) with strongelectron-withdrawing functionalities.

As used herein, a compound can be considered soluble in a solvent whenat least 0.1 mg of the compound can be dissolved in 1 mL of the solvent.Examples of common organic solvents include petroleum ethers;acetonitrile; aromatic hydrocarbons such as benzene, toluene, xylene,and mesitylene; ketones such as acetone, and methyl ethyl ketone; etherssuch as tetrahydrofuran, dioxane, bis(2-methoxyethyl) ether, diethylether, di-isopropyl ether, and t-butyl methyl ether; alcohols such asmethanol, ethanol, butanol, and isopropyl alcohol; aliphatichydrocarbons such as hexanes; esters such as methyl acetate, ethylacetate, methyl formate, ethyl formate, isopropyl acetate, and butylacetate; amides such as dimethylformamide and dimethylacetamide;sulfoxides such as dimethylsulfoxide; halogenated aliphatic and aromatichydrocarbons such as dichloromethane, chloroform, ethylene chloride,chlorobenzene, dichlorobenzene, and trichlorobenzene; and cyclicsolvents such as cyclopentanone, cyclohexanone, and 2-methypyrrolidone.

As used herein, “solution-processable” refers to compounds (e.g.,thienocoronene-imide copolymers), materials, or compositions that can beused in various solution-phase processes including spin-coating,printing (e.g., inkjet printing, screen printing, pad printing, offsetprinting, gravure printing, flexographic printing, lithographicprinting, mass-printing and the like), spray coating, electrospraycoating, drop casting, dip coating, and blade coating.

The present teachings, therefore, further provide methods of preparing asemiconductor material. The methods can include preparing a compositionthat includes one or more compounds disclosed herein dissolved ordispersed in a liquid medium such as a solvent or a mixture of solvents,depositing the composition on a substrate to provide a semiconductormaterial precursor, and processing (e.g., heating) the semiconductorprecursor to provide a semiconductor material (e.g., a thin filmsemiconductor) that includes a compound disclosed herein. In variousembodiments, the liquid medium can be an organic solvent, an inorganicsolvent such as water, or combinations thereof. In some embodiments, thecomposition can further include one or more additives independentlyselected from viscosity modulators, detergents, dispersants, bindingagents, compatiblizing agents, curing agents, initiators, humectants,antifoaming agents, wetting agents, pH modifiers, biocides, andbactereriostats. For example, surfactants and/or polymers (e.g.,polystyrene, polyethylene, poly-alpha-methylstyrene, polyisobutene,polypropylene, polymethylmethacrylate, and the like) can be included asa dispersant, a binding agent, a compatiblizing agent, and/or anantifoaming agent. In some embodiments, the depositing step can becarried out by printing, including inkjet printing and various contactprinting techniques (e.g., screen-printing, gravure printing, offsetprinting, pad printing, lithographic printing, flexographic printing,and microcontact printing). In other embodiments, the depositing stepcan be carried out by spin coating, drop-casting, zone casting, dipcoating, blade coating, or spraying.

Compounds of the present teachings can be used to prepare semiconductormaterials (e.g., compositions and composites), which in turn can be usedto fabricate various articles of manufacture, structures, and devices.In some embodiments, semiconductor materials incorporating one or morecompounds of the present teachings can exhibit p-type semiconductoractivity, ambipolar activity, light absorption, and/or light emission.

The present teachings, therefore, further provide methods of preparing asemiconductor material. The methods can include preparing a compositionthat includes one or more compounds disclosed herein dissolved ordispersed in a liquid medium such as a solvent or a mixture of solvents,depositing the composition on a substrate to provide a semiconductormaterial precursor, and processing (e.g., heating) the semiconductorprecursor to provide a semiconductor material (e.g., a thin filmsemiconductor) that includes a compound disclosed herein. In variousembodiments, the liquid medium can be an organic solvent, an inorganicsolvent such as water, or combinations thereof. In some embodiments, thecomposition can further include one or more additives independentlyselected from viscosity modulators, detergents, dispersants, bindingagents, compatiblizing agents, curing agents, initiators, humectants,antifoaming agents, wetting agents, pH modifiers, biocides, andbactereriostats. For example, surfactants and/or polymers (e.g.,polystyrene, polyethylene, poly-alpha-methylstyrene, polyisobutene,polypropylene, polymethylmethacrylate, and the like) can be included asa dispersant, a binding agent, a compatiblizing agent, and/or anantifoaming agent. In some embodiments, the depositing step can becarried out by printing, including inkjet printing and various contactprinting techniques (e.g., screen-printing, gravure printing, offsetprinting, pad printing, lithographic printing, flexographic printing,and microcontact printing). In other embodiments, the depositing stepcan be carried out by spin coating, drop-casting, zone casting, dipcoating, blade coating, or spraying.

Various articles of manufacture including electronic devices, opticaldevices, and optoelectronic devices, such as thin film semiconductors,field effect transistors (e.g., thin film transistors), photovoltaics,photodetectors, organic light emitting devices such as organic lightemitting diodes (OLEDs) and organic light emitting transistors (OLETs),complementary metal oxide semiconductors (CMOSs), complementaryinverters, diodes, capacitors, sensors, D flip-flops, rectifiers, andring oscillators, that make use of the compounds disclosed herein arewithin the scope of the present teachings as are methods of making thesame. The present compounds can offer processing and operationadvantages in the fabrication and/or the use of these devices.

For example, articles of manufacture such as the various devicesdescribed herein can be an electronic or optoelectronic device includinga first electrode, a second electrode, and a semiconducting component incontact with the first electrode and the electrode, where thesemiconducting component includes a compound of the present teachings.These devices can include a composite having a semiconducting component(or semiconductor material) of the present teachings and a substratecomponent and/or a dielectric component. The substrate component can beselected from doped silicon, an indium tin oxide (ITO), ITO-coatedglass, ITO-coated polyimide or other plastics, aluminum or other metalsalone or coated on a polymer or other substrate, a doped polythiophene,and the like. The dielectric component can be prepared from inorganicdielectric materials such as various oxides (e.g., SiO₂, Al₂O₃, HfO₂),organic dielectric materials such as various polymeric materials (e.g.,polycarbonate, polyester, polystyrene, polyhaloethylene, polyacrylate),and self-assembled superlattice/self-assembled nanodielectric (SAS/SAND)materials (e.g., as described in Yoon, M-H. et al., PNAS, 102 (13):4678-4682 (2005), the entire disclosure of which is incorporated byreference herein), as well as hybrid organic/inorganic dielectricmaterials (e.g., described in U.S. patent application Ser. No.11/642,504, the entire disclosure of which is incorporated by referenceherein). In some embodiments, the dielectric component can include thecrosslinked polymer blends described in U.S. patent application Ser.Nos. 11/315,076, 60/816,952, and 60/861,308, the entire disclosure ofeach of which is incorporated by reference herein. The composite alsocan include one or more electrical contacts. Suitable materials for thesource, drain, and gate electrodes include metals (e.g., Au, Al, Ni,Cu), transparent conducting oxides (e.g., ITO, IZO, ZITO, GZO, GIO,GITO), and conducting polymers (e.g.,poly(3,4-ethylenedioxythiophene)poly(styrenesulfonate) (PEDOT:PSS),polyaniline (PANI), polypyrrole (PPy)). One or more of the compositesdescribed herein can be embodied within various organic electronic,optical, and optoelectronic devices such as organic thin filmtransistors (OTFTs), specifically, organic field effect transistors(OFETs), as well as sensors, capacitors, unipolar circuits,complementary circuits (e.g., inverter circuits), and the like.

Accordingly, an aspect of the present teachings relates to methods offabricating an organic field effect transistor that incorporates asemiconductor material of the present teachings. The semiconductormaterials of the present teachings can be used to fabricate varioustypes of organic field effect transistors including top-gate top-contactcapacitor structures, top-gate bottom-contact capacitor structures,bottom-gate top-contact capacitor structures, and bottom-gatebottom-contact capacitor structures.

FIG. 1 illustrates the four common types of OFET structures: (a)bottom-gate top-contact structure, (b) bottom-gate bottom-contactstructure, (c) top-gate bottom-contact structure, and (d) top-gatetop-contact structure. As shown in FIG. 1, an OFET can include a gatedielectric component (e.g., shown as 8, 8′, 8″, and 8′″), asemiconducting component or semiconductor layer (e.g., shown as 6, 6′,6″, and 6′″), a gate electrode or contact (e.g., shown as 10, 10′, 10″,and 10′″), a substrate (e.g., shown as 12, 12′, 12″, and 12′″), andsource and drain electrodes or contacts (e.g., shown as 2, 2′, 2″, 2′″,4, 4′, 4″, and 4′″). As shown, in each of the configurations, thesemiconducting component is in contact with the source and drainelectrodes and the gate dielectric component.

In certain embodiments, OTFT devices can be fabricated with the presentcompounds on doped silicon substrates, using SiO₂ as the dielectric, intop-contact geometries. In particular embodiments, the activesemiconductor layer which incorporates at least a compound of thepresent teachings can be deposited at room temperature or at an elevatedtemperature. In other embodiments, the active semiconductor layer whichincorporates at least one compound of the present teachings can beapplied by spin-coating or printing as described herein. For top-contactdevices, metallic contacts can be patterned on top of the films usingshadow masks.

In certain embodiments, OTFT devices can be fabricated with the presentcompounds on plastic foils, using polymers as the dielectric, intop-gate bottom-contact geometries. In particular embodiments, theactive semiconducting layer which incorporates at least a compound ofthe present teachings can be deposited at room temperature or at anelevated temperature. In other embodiments, the active semiconductinglayer which incorporates at least a compound of the present teachingscan be applied by spin-coating or printing as described herein. Gate andsource/drain contacts can be made of Au, other metals, or conductingpolymers and deposited by vapor-deposition and/or printing.

In various embodiments, a semiconducting component incorporatingcompounds of the present teachings can exhibit semiconducting activity,for example, a carrier mobility of 10⁻⁴ cm²/V-sec or greater and/or acurrent on/off ratio (I_(on)/I_(off)) of 10³ or greater.

Other articles of manufacture in which compounds of the presentteachings are useful are photovoltaics or solar cells. Compounds of thepresent teachings can exhibit broad optical absorption and/or a tunedredox properties and bulk carrier mobilities, making them desirable forsuch applications. Accordingly, the compounds described herein can beused as a donor (p-type) semiconductor material in a photovoltaicdesign, which includes an adjacent n-type semiconductor material thatforms a p-n junction. The compounds can be in the form of a thin filmsemiconductor, which can be deposited on a substrate to form acomposite. Exploitation of compounds of the present teachings in suchdevices is within the knowledge of a skilled artisan.

In various embodiments, a semiconducting component incorporatingcompounds of the present teachings can enable photovoltaic cells withpower conversion efficiency of about 1% or greater.

Accordingly, another aspect of the present teachings relates to methodsof fabricating an organic light-emitting transistor, an organiclight-emitting diode (OLED), or an organic photovoltaic device thatincorporates one or more semiconductor materials of the presentteachings. FIG. 2 illustrates a representative structure of abulk-heterojunction organic photovoltaic device (also known as solarcell) which can incorporate one or more compounds of the presentteachings as the donor and/or acceptor materials. As shown, arepresentative solar cell generally includes a substrate 20 (e.g.,glass), an anode 22 (e.g., ITO), a cathode 26 (e.g., aluminium orcalcium), and a photoactive layer 24 between the anode and the cathodewhich can incorporate one or more compounds of the present teachings asthe electron donor (p-channel) and/or electron acceptor (n-channel)materials. Optional interlayers (not shown) also can be present. FIG. 3illustrates a representative structure of an OLED which can incorporateone or more compounds of the present teachings as electron-transportingand/or emissive and/or hole-transporting materials. As shown, an OLEDgenerally includes a substrate 30 (not shown), a transparent anode 32(e.g., ITO), a cathode 40 (e.g., metal), and one or more organic layerswhich can incorporate one or more compounds of the present teachings ashole-transporting (n-channel) (layer 34 as shown) and/or emissive (layer36 as shown) and/or electron-transporting (p-channel) materials (layer38 as shown). In embodiments where the present compounds only have oneor two of the properties of hole transport, electron transport, andemission, the present compounds can be blended with one or more furtherorganic compounds having the remaining required property or properties.

The following examples are provided to illustrate further and tofacilitate the understanding of the present teachings and are not in anyway intended to limit the invention.

N-Bromosuccinimide (NBS), n-butyllithium (2.5 M in hexanes), BF₃.OEt₂,Me₃SnCl and Pd(PPh₃)₄ were purchased from Aldrich.Bis(2,2-diethoxyethyl)disulfide was purchased from TCI America. NBS wasrecrystallized from H₂O and all other reagents commercially availablewere used as received without further purification.

THF was distilled from Na/benzophenone. All reactions were carried outunder an inert atmosphere of N₂. Analytical thin-layer chromatography(TLC) was performed on aluminum sheets, precoated with silica gel60-F₂₅₄ (Merck 5554). Flash column chromatography was carried out usingsilica gel 60 (Silicycle) as the stationary phase. NMR spectra wererecorded on either a Bruker Avance III 500 spectrometer or a VarianUnity Plus 500 spectrometer, with working frequencies of 499.4 MHz for¹H and 125.6 MHz for ¹³C. Chemical shifts are reported in ppm andreferenced to the residual non-deuterated solvent frequencies (CDCl₃: δ7.27 ppm for ¹H, δ 77.0 ppm for ¹³C). High resolution mass spectra wererecorded on an Agilent 6210 LC-TOF multimode ionization (MMI) massspectrometer. Electrospray mass spectrometry was performed with a ThermoFinnegan model LCQ Advantage mass spectrometer. UV-Visible spectroscopywas performed on a Varian Cary 5000 UV-Vis-NIR spectrophotometer or aVarian Cary 50 Scan UV-Vis spectrophotometer. Electrochemistry wasperformed on a C3 Cell Stand electrochemical station equipped with BASEpsilon software (Bioanalytical Systems, Inc., Lafayette, Ind.).Photoreactions with UV irradiation was carried out in a photochemicalreactor Rayonet model RPR 600 MINI (Southern New England UltravioletCompany) equipped with 254 nm UV ramp. Differential scanning calorimetry(DSC) was performed on TA model DSC 2920 with a heating ramp of 10°C./min and reported for the second heating-cooling cycle. Polymermolecular weights were determined on a Polymer Laboratories PL-GPC 220using trichlorobenzene as eluent at 150° C. versus polystyrenestandards. OFET device measurements were carried out at room temperaturein a customized probe station in air. Coaxial and/or triaxial shieldingwas incorporated into Signatone probes to minimize noise levels. Organicfield effect transistor (OFET) characterizations were performed with aKeithley 6430 subfemto ammeter (drain) and a Keithley 2400 (gate) sourcemeter, operated by a locally written Labview program. Thin films wereanalyzed using wide-angle X-ray diffractometry (WAXRD) on a Rigaku ATX-Gusing standard θ-2 θtechniques, with monochromatic CuKα radiation.Tapping mode atomic force microscopy (AFM) was performed with a BrukerDimension ICON. OPV characterization was performed on a Spectra-NovaClass A Solar Simulator with AM1.5G light (100 mW/cm₂) from a Xe arclamp. The light source was calibrated with an NREL-certified Si diodeequipped with a KG3 filter to bring spectral mismatch to unity. Currentvs potential (J-V) measurements were recorded with a Keithly 2400digital source meter. External quantum efficiency (EQE) was performedusing an Oriel Model S3 QE-PV-SI (Newport Instruments) equipped with anNIST-certified Si-diode and a Merlin lock-in amplifier and opticalchopper. Monochromatic light was generated from a 300 W Xe arc lamp.

Example 1 Synthesis of Dialkoxy NDT and BDT Derivatives

Scheme 1 shows a synthetic route of5,10-dialkoxynaphtho[2,3-b:6,7-b′]dithiophene (4a-c) and its2,7-bis(trimethyltin)- (5a-c) and 2,7-dibromo- (6a) derivatives, as wellas BDT derivatives as comparative compounds (7a-c and 8b-c). In thisroute, methoxy-substituted NDT (3) was synthesized first, then atrans-etherification reaction was used to convert (3) to NDTs withvarious alkoxy side chains. While it also is possible to introduce thealkoxy chains before the ring-closure reaction, the synthetic routeshown in Scheme 1 allows introduction of the alkoxy side chains at theend of the monomer synthesis, thereby enabling NDTs with various sidechains to be prepared conveniently from a stock of methoxy NDT (3).

2,6-Bis[(2,2-diethoxyethyl)sulfanyl]-1,5-dimethoxynaphthalene (2)

2,6-Dibromo-1,5-dimethoxynaphthalene (1) (2.00 g, 5.78 mmol),synthesized from 2,6-dibromo-1,5-dihydroxynaphthalene as described inWheeler et al., J. Org. Chem. 1930, 52, 4872), was solubilized inanhydrous THF (190 mL) and cooled at −78° C. under N₂. n-Butyllithium(5.8 mL, 2.5M) was then added and the stirring was continued for 2hours. The reaction mixture was treated withbis(2,2-diethoxyethyl)disulfide (4.66 g, 15.6 mmol) and kept at −78° C.for 30 minutes, then warmed up to room temperature and stirredovernight. The reaction was stopped by adding water, and the mixture wasextracted with diethyl ether, dried over MgSO₄, filtered, andconcentrated in vacuo. The crude product was purified by columnchromatography (30% ethyl acetate in hexanes) to afford 1.46 g of ayellow oil. (Yield=52%). ¹H NMR (500 MHz, CDCl₃, 298 K): 7.80 (d, J=8.9Hz, 2H); 7.51 (d, J=8.6 Hz, 2H); 4.68 (t, J=5.3 Hz, 2H); 3.99 (s, 6H);3.68 (quintet, J=7.1 Hz, 4H); 3.56 (quintet, J=7.1 Hz, 4H); 3.23 (d,J=5.7 Hz, 4H); 1.19 (t, J=6.9 Hz, 12H) ppm. ¹³C NMR (125 MHz, CDCl₃, 298K): 154.46; 128.40; 128.14; 125.20; 118.24; 101.91; 62.17; 61.11; 36.28;15.25 ppm. HRMS (ESI-TOF-MS): m/z calcd for C₂₄H₃₆O₆S₂ [M+Na]507.1846.found 507.1853.

5,10-Dimethoxynaphtho[2,3-b:6,7-b′]dithiophene (3)

Polyphosphoric acid (2.90 g) was dissolved in chlorobenzene (90 mL) andheated at reflux for 3 hours. A solution of compound (2) (2.25 g, 4.64mmol) in chlorobenzene (17 mL) was added dropwise to the reactionmixture. Stirring was pursued for 24 hours before evaporatingchlorobenzene. The crude product was solubilized in dichloromethane,washed with NaHCO₃ and water. The solution was dried over MgSO₄ andconcentrated in vacuo. The product was purified by flash columnchromatography (40% dichloromethane in hexanes) to afford 0.589 g of thetitle compound as a yellow powder. (Yield=42%). ¹H NMR (500 MHz, CDCl₃,298 K): 8.51 (s, 2H); 7.49 (m, 4H); 4.25 (s, 6H) ppm. ¹³C NMR (125 MHz,CDCl₃, 298 K): 149.37; 138.81; 127.20; 126.14; 123.61; 123.38; 109.95;59.64 ppm. HRMS (ESI-TOF-MS): m/z calcd for C₁₆H₁₂O₂S₂ 300.0273. found300.0264.

5,10-Bis(2-octyldodecyloxy)naphtho[2,3-b:6,7-b′]dithiophene (4a)

Compound (3) (0.400 g, 1.33 mmol) was weighed into a flame-dried 2-neckflask fitted with a condenser. Toluene (13 mL), 2-octyl-1-dodecanol(1.59 g, 5.32 mmol), and p-toluenesulfonic acid (0.051 g, 0.266 mmol)were then added. The mixture was placed in a 130° C. heat bath andstirred overnight. The mixture was diluted with water, extracted withdichloromethane, dried over MgSO₄, filtered and concentrated. Theproduct was purified via column chromatography (10% dichloromethane inhexanes) to yield compound (4a) as a yellow solid (0.735 g, 66%). ¹H NMR(500 MHz, CDCl₃, 298 K): 8.46 (s, 2H); 7.45 (m, 4H); 4.27 (d, J=5.4 Hz,4H); 2.01 (quintet, J=6.2 Hz, 2H); 1.73 (m, 4H); 1.47 (m, 60H); 0.89 (m,12H) ppm. ¹³C NMR (125 MHz, CDCl₃, 298 K): 149.87; 139.70; 127.98;127.08; 124.83; 124.62; 110.84; 75.85; 39.38; 31.96; 31.42; 30.18;29.76; 29.71; 29.43; 29.41; 27.06; 22.74; 14.18 ppm. HRMS (ESI-TOF-MS):m/z calcd for C₅₄H₈₈O₂S₂ 832.6220. found 832.6217.

5,10-Ditetradecyloxynaphtho[2,3-b:6,7-b′]dithiophene (4b)

Compound (3) (0.500 g, 1.66 mmol) was weighed into a flame-dried 2-neckflask fitted with a condenser. Toluene (17 mL), 1-tetradecanol (1.42 g,6.64 mmol), and p-toluenesulfonic acid (0.063 g, 0.332 mmol) were thenadded. The mixture was placed in a 130° C. heat bath and stirredovernight. The mixture was diluted with water, extracted withdichloromethane, dried over MgSO₄, filtered, and concentrated. Theproduct was purified via column chromatography (20% dichloromethane inhexanes) to yield compound (4b) as a yellow solid (0.540 g, 49%). ¹H NMR(500 MHz, CDCl₃, 298 K): 8.48 (s, 2H); 7.47 (m, 4H); 4.38 (t, J=6.6 Hz,4H); 2.02 (quintet, J=7.7 Hz, 4H); 1.65 (quintet, J=7.8 Hz, 4H); 1.39(m, 40H); 0.89 (t, J=7.1 Hz 6H) ppm. ¹³C NMR (125 MHz, CDCl₃, 298 K):149.74; 139.68; 128.05; 127.36; 124.87; 124.64; 110.97; 73.54; 31.96;30.66; 29.73; 29.70; 29.54; 29.40; 26.18; 22.73; 14.17 ppm. HRMS(ESI-TOF-MS): m/z calcd for C₄₂H₆₄O₂S₂664.4348. found 664.4356.

5,10-Diethylhexyloxynaphtho[2,3-b:6,7-b′]dithiophene (4c)

n-Butyllithium (2.5 M solution in hexane, 13.0 mL, 32.5 mmol) was addeddropwise to a solution of 2,6-dibromo-1,5-diethylhexyloxynaphthalene(7.04 g, 13.0 mmol) in dry THF (240 ml) at −78° C. The mixture wasstirred at this temperature for 2 h and thenbis(2,2-diethoxyethyl)disulfide (10.5 g, 35.2 mmol) was added. Afterstirring for 30 min, the reaction was allowed to warm up to roomtemperature and stirred overnight. The reaction was quenched with waterand extracted with ether (3 Å-100 mL), then dried over MgSO₄, filtered,and concentrated in vacuo. Volatile impurities were further removed invacuo at 150° C. The residue was chromatographed on SiO₂ (hexanes-EtOAc,gradient from 99:1 to 97:3) to afford2,6-bis[(2,2-diethoxyethyl)sulfanyl]-1,5-diethylhexyloxynaphthalene as ayellow oil (6.36 g, 72%). ¹H NMR (500 MHz, CDCl₃, 298 K): 8=7.77 (d,J=9.0 Hz, 2H), 7.49 (d, J=9.0 Hz, 2H), 4.65 (t, J=5.5 Hz, 2H), 3.96 (d,J=6.0 Hz, 4H), 3.97-3.51 (m, 8H), 3.21 (d, J=5.5 Hz, 4H), 1.94-1.86 (m,2H), 1.76-1.35 (m, 16H), 1.18 (t, J=7.0 Hz, 12H), 1.03 (t, J=7.0 Hz,6H), 0.95 (t, J=7.0 Hz, 6H) ppm. ¹³C NMR (125 MHz, CDCl₃, 298 K):∂=153.8, 128.7, 128.1, 125.1, 118.0, 102.0, 76.4, 62.1, 40.7, 36.4,30.3, 29.2, 23.7, 23.1, 15.2, 14.2, 11.3 ppm. Anal. Calcd forC₃₈H₆₄O₆S₂: C, 67.02; H, 9.47. Found: C, 67.71; H, 9.39.

A solution of2,6-bis[(2,2-diethoxyethyl)sulfanyl]-1,5-diethylhexyloxynaphthalene(4.89 g, 7.18 mmol) in dry CH₂Cl₂ (800 mL) was added dropwise over 4.5 hto a refluxing solution of BF₃.OEt₂ (2.0 mL, 16 mmol) in dry CH₂Cl₂(2000 mL). The mixture was refluxed overnight and poured into sat.NaHCO₃ (aq) (1000 mL) and cooled to ambient temperature. The organiclayer was separated and combined with CH₂Cl₂ extracts (2 Å˜100 mL),dried over MgSO₄, filtered, and concentrated. The residue waschromatographed on SiO₂ (hexanes-EtOAc, gradient from 100:0 to 99.3:0.7)to afford the title compound as a yellow powder (495 mg, 14%). ¹H NMR(500 MHz, CDCl₃, 298 K): ∂=8.47 (s, 2H), 7.46 (m, 4H), 4.28 (d, J=5.5Hz, 4H), 2.00-1.93 (m, 2H), 1.84-1.40 (m, 16H), 1.08 (t, J=7.5 Hz, 6H),0.95 (t, J=7.5 Hz, 6H) ppm. ¹³C NMR (125 MHz, CDCl₃, 298 K): ∂=149.8,139.7, 128.0, 127.1, 124.8, 124.6, 110.8, 75.5, 40.8, 30.5, 29.2, 23.9,23.2, 14.2, 11.4 ppm. Anal. Calcd for C₃₀H₄₀O₂S₂: C, 72.53; H, 8.12.Found: C, 72.68; H, 8.16.

2,7-Bis(trimethylstannyl)-5,10-bis(2-octyldodecyloxy)naphtho[2,3-b:6,7-b′]dithiophene(5a)

Compound (4a) (0.350 g, 0.420 mmol) was solubilized in anhydrous THF (17mL) and cooled at −78° C. under N₂. n-Butyllithium (0.42 mL, 2.5M) wasthen added and the stirring was continued for 30 minutes at thistemperature and then 30 minutes at room temperature. The reactionmixture was cooled to −78° C. again before adding trimethylstannylchloride (1.1 mL, 1.0M). The reaction was warmed up to room temperatureand stirred overnight. The reaction was stopped by adding water, and themixture was extracted with diethyl ether, dried over MgSO₄, filtered,and concentrated in vacuo. The crude monomer was solubilized in 5 mL ofTHF and then dropped in methanol (200 mL). The product was allowed toprecipitate in the freezer overnight before filtering and washing withcold methanol to afford a yellow fluffy powder as the title compound(0.420 g, 86%). ¹H NMR (500 MHz, CDCl₃, 298 K): 8.43 (s, 2H); 7.51 (s,2H); 4.29 (d, J=5.4 Hz, 4H); 2.00 (quintet, J=6.0 Hz, 2H); 1.74 (m, 4H);1.45 (m, 60H); 0.88 (m, 12H); 0.47 (s, 18H) ppm. ¹³C NMR (125 MHz,CDCl₃, 298 K): 149.22; 142.73; 141.25; 132.62; 130.19; 124.51; 109.71;75.50; 39.37; 31.99; 31.97; 31.42; 30.23; 29.83; 29.82; 29.78; 29.75;29.47; 29.42; 27.08; 22.74; 14.19; 14.18; 8.40 ppm. HRMS (ESI-TOF-MS):m/z calcd for C₆₀H₁₀₄O₂S₂Sn₂ 1158.5516. found 1158.5543.

2,7-Bis(trimethylstannyl)-5,10-ditetradecyloxynaphtho[2,3-b:6,7-b′]dithiophene(5b)

Compound (4b) (0.500 g, 0.752 mmol) was solubilized in anhydrous THF (40mL) and cooled at −78° C. under N₂. n-Butyllithium (0.75 mL, 2.5M) wasthen added and the stirring was continued for 30 minutes at thistemperature and then 30 minutes at room temperature. The reactionmixture was cooled to −78° C. again before adding trimethylstannylchloride (1.9 mL, 1.0M). The reaction was warmed up to room temperatureand stirred overnight. The reaction was stopped by adding water, and themixture was extracted with diethyl ether, dried over MgSO₄, filtered,and concentrated in vacuo. The crude monomer was solubilized in 5 mL ofTHF and then dropped in methanol (200 mL). The product was allowed toprecipitate in the freezer overnight before filtering and washing withcold methanol to afford a yellow fluffy powder as the title compound(0.650 g, 86%). ¹H NMR (500 MHz, CDCl₃, 298 K): 8.45 (s, 2H); 7.53 (s,2H); 4.38 (t, J=6.6 Hz, 4H); 2.01 (quintet, J=7.9 Hz, 4H); 1.65(quintet, J=7.7 Hz, 4H); 1.39 (m, 40H); 0.89 (t, J=7.0 Hz 6H); 0.47 (s,18H) ppm. ¹³C NMR (125 MHz, CDCl₃, 298 K): 149.07; 142.85; 141.22;132.66; 130.48; 124.58; 109.85; 73.20; 31.96; 30.65; 29.76; 29.73;29.70; 29.57; 29.41; 26.17; 22.73; 14.17; 8.38 ppm. HRMS (ESI-TOF-MS):m/z calcd for C₄₈H₈₀O₂S₂Sn₂ 990.3638. found 990.3670.

2,7-Bis(trimethylstannyl)-5,10-bis(2-ethylhexyloxy)naphtho[2,3-b:6,7-b′]dithiophene(5c)

n-Butyllithium (2.5 M solution in hexane, 0.6 mL, 1.5 mmol) was addeddropwise to a solution of compound (4c) (295.3 mg, 0.595 mmol) in dryTHF (50 mL) at −78° C. The mixture was stirred at this temperature for30 min and then at room temperature for 30 min. After cooling down to−78° C., Me₃SnCl (1 M solution in hexane, 1.5 mL, 1.5 mmol) was addeddropwise. After stirring for 30 min at this temperature, the reactionwas returned to room temperature and stirred overnight. The reaction wasquenched with NaHCO₃ (aq) and solvent was removed in vacuo. The residuewas dissolved in hexane and washed with NaHCO₃ aq (1 Å-25 mL) and withwater (2 Å˜25 mL), then dried over MgSO₄, filtered, and concentrated invacuo. Recrystallization in iPrOH yielded the target compound as ayellow powder (411.2 mg, 84%). ¹H NMR (500 MHz, CDCl₃, 298 K): ∂=8.44(s, 2H), 7.52 (s, 2H), 4.30 (d, J=5.5 Hz, 4H), 2.00-1.92 (m, 2H),1.84-1.40 (m, 16H), 1.08 (t, J=7.5 Hz, 6H), 0.98 (t, J=7.0 Hz, 6H), 0.48(s, 18H) ppm. ¹³C NMR (125 MHz, CDCl₃, 298 K): ∂=149.2, 142.7, 141.2,132.6, 130.1, 124.5, 109.6, 75.2, 40.8, 30.5, 29.2, 23.9, 23.2, 14.2,11.4, −8.4 ppm. Anal. Calcd for C₃₆H₅₆O₂S₂Sn₂: C, 52.58; H, 6.86. Found:C, 53.03; H, 6.86.

2,7-Dibromo-5,10-bis(2-octyldodecyl)oxynaphtho[2,3-b:6,7-b′]dithiophene(6a)

Compound (4a) (0.268 g, 0.322 mmol) was solubilized in anhydrous THF (21mL) and cooled at −78° C. under N₂. n-Butyllithium (0.32 mL, 2.5M) wasthen added and the stirring was continued for 30 minutes at thistemperature and then 30 minutes at room temperature. The reactionmixture was cooled to −78° C. again before adding carbon tetrabromide(0.267 g, 0.805 mmol). The reaction was warmed up to room temperatureand stirred overnight. The reaction was stopped by adding water, and themixture was extracted with diethyl ether, dried over MgSO₄, filtered,and concentrated in vacuo. The crude monomer was solubilized in 5 mL ofTHF and then dropped in methanol (200 mL). The product was allowed toprecipitate in the freezer overnight before filtering and washing withcold methanol to afford an orange powder as the title compound (0.226 g,71%). ¹H NMR (500 MHz, CDCl₃, 298 K): 8.25 (s, 2H); 7.43 (s, 2H); 4.19(d, J=5.5 Hz, 4H); 1.96 (quintet, J=5.9 Hz, 2H); 1.68 (m, 4H); 1.44 (m,60H); 0.90 (m, 12H) ppm. ¹³C NMR (125 MHz, CDCl₃, 298 K): 148.76;139.25; 128.40; 127.21; 124.71; 117.73; 110.02; 76.00; 39.30; 31.97;31.33; 30.13; 29.76; 29.75; 29.72; 29.42; 27.01; 22.74; 14.19 ppm. HRMS(ESI-TOF-MS): m/z calcd for C₅₄H₈₆Br₂O₂S₂ 988.4431. found 988.4418.

Compounds (7a), (7b), (7c), (8b), and (8c) were prepared according tothe procedures described in Launay, J.-P. et al., J. Phys. Chem. B,2007, 111, 6788-6797; Hou, J. et al., Macromolecules, 2008, 41,6012-6018; and Liang, Y. et al., J. Am. Chem. Soc. 2009, 131, 7792-7799.

Example 2 Characterization of Monomers

UV/Vis absorption spectra of NDT with 2-ethylhexyl chains (4c) andanalogous BDT (7c) were recorded in dichloromethane solution (5 μM). Asshown in FIG. 4, NDT presents a broad and strong absorption up to 430nm, which is a red-shift of ˜60 nm compared to BDT and reasonablyconfirms its extended π-conjugation. Cyclic voltammograms of 4c and 7cwere recorded using a dichloromethane solution in the presence oftetrabutylammonium hexafluorophosphate (Bu₄NPF₆, 0.1 M) as theelectrolyte, and showed their oxidation potentials at 0.34 V and 0.45 Vvs. ferrocene/ferrocenium, respectively. This result indicates that HOMOlevel of NDT is 0.11 eV higher than that of BDT, which is suitable forNDT to work as a more conjugated alternative to BDT to givesemiconductor materials with similar or slightly higher HOMO levels.

Example 3 Synthesis of Polymer Semiconductors

Scheme 3 shows the synthesis of several different embodiments of thepresent semiconducting polymers based on NDT: the homopolymer P1, thecopolymer with thiophene P2, the copolymer with bithiophene P3, and thecopolymer with thiophene-capped diketopyrrolopyrrole (TDPP) P4 a-b.Branched and long alkyl chains (2-octyldodecyl) were employed in P1-P3to ensure the solution processability. For P4 a-b, linear alkyl chains(n-tetradecyl) and shorter branched alkyl chains (2-ethylhexyl and2-butyloctyl) were employed, as the alkyl side chains of comonomer TDPPcould help solubility of the resulting copolymers. Copolymers with BDTand TDPP with linear side chains (P5 a) and branched side chains (P5 b)were also synthesized for comparison to P4 a and P4 b, respectively.Generally, P1-P5 can be synthesized by Stille coupling reaction usingstannylated NDTs (5a-c) or stannylated BDTs (8b-c) and correspondingbrominated comonomers shown in Scheme 3. All polymers have goodsolubility for device fabrication (at least 5 mg/mL) in chloroform or inchlorobenzene.

General Procedure for Synthesis of P1-P3:

The two monomers, Pd₂dba₃ (2.8%) and P(o-tol)₃ (11.2%) were loaded in aflame-dried one neck flask mounted with a condenser. Dry and degassedtoluene (5 mL) was then added and the reaction was heated to 110° C.under nitrogen for 24 hours. Afterward, end-capping reaction wasperformed by adding 10% of 2-bromothiophene and 4 hours later 10% of2-(tributylstannyl)thiophene. After 2 additional hours of stirring thereaction was allowed to cool down to room temperature and dropped into250 mL of methanol. The resulting solids were subjected to Soxhletextraction with acetone and hexanes and then dissolved in chloroform.The soluble fraction was concentrated under vacuum, precipitated inmethanol, and filtered to give the polymers as dark red solids.

Polymer P1:

This product was obtained as a dark red solid (48% yield). ¹H NMR (500MHz, CDCl₃, 298 K): 8.35 (br, 2H); 7.71 (br 2H); 4.22 (br, 4H); 1.28(br, 66H); 0.80 (br, 12H) ppm. M_(n)=13.7 kg/mol, M_(w)=301.6 kg/mol,PDI=22.0.

Polymer P2:

This product was obtained as a dark red solid (95% yield). ¹H NMR (500MHz, CDCl₃, 298 K): 7.74 (br, 2H); 6.95 (br, 4H); 4.15 (br, 4H); 1.32(br, 66H); 0.82 (br, 12H) ppm. M_(n)=15.5 kg/mol, M_(w)=48.5 kg/mol,PDI=3.1.

Polymer P3:

This product was obtained as a dark red solid (34% yield). ¹H NMR (500MHz, CDCl₃, 298 K): 7.07 (br, 4H); 6.70 (br, 4H); 4.06 (br, 4H); 1.29(br, 66H); 0.84 (m, 12H) ppm. M_(n)=15.7 kg/mol, M_(w)=101.5 kg/mol,PDI=6.5.

Synthesis of Monomers 13a and 13b:

2,5-Ditetradecyl-3,6-di(thien-2-yl)pyrrolo[3,4-c]pyrrole-1,4-dione (14a)

TDPP (2.20 g, 7.33 mmol) and K₂CO₃ (4.20 g, 30.4 mmol) were solubilizedin anhydrous DMF (50 mL) and heated up to 145° C. under N₂. n-tetradecylbromide (9.40 g, 33.9 mmol) was then added and the stirring wascontinued overnight at this temperature. The reaction was cooled down toroom temperature and poured into iced water (100 g) and extracted withchloroform. The extract was dried over MgSO₄, filtered, concentrated invacuo, and then chromatographed on SiO₂ (30% hexanes in chloroform) toafford a dark purple powder as the title compound (2.31 g, 46%). ¹H NMR(500 MHz, CDCl₃, 298 K): 8.94 (m, 2H); 7.65 (m, 2H); 7.30 (m, 2H); 4.08(t, J=7.9 Hz, 4H); 1.75 (quintet, J=7.8 Hz, 4H); 1.42 (quintet, J=7.5Hz, 4H); 1.26 (m, 40H); 0.88 (t, J=7.1 Hz, 6H) ppm. ¹³C NMR (125 MHz,CDCl₃, 298 K): 161.36; 140.01; 135.26; 130.69; 129.75; 128.60; 107.74;42.21; 32.79; 31.91; 29.94; 29.64; 29.56; 29.52; 29.42; 29.35; 29.24;26.86; 25.71; 22.69; 14.13 ppm. HRMS (ESI-TOF-MS): m/z calcd forC₄₂H₆₄N₂O₂S₂ [M+H]⁺ 693.4482. found 693.4473.

2,5-Bis(2-butyloctyl)-3,6-di(thien-2-yl)pyrrolo[3,4-c]pyrrole-1,4-dione(14b)

TDPP (2.20 g, 7.33 mmol) and K₂CO₃ (4.21 g, 30.5 mmol) was solubilizedin anhydrous DMF (50 mL) and heated up to 145° C. under N₂. 2-Butyloctylbromide (8.55 g, 34.3 mmol) was then added and the stirring wascontinued overnight at this temperature. The reaction was cooled down toroom temperature and poured into iced water (100 g) and filtered withsuction. The solid was dissolved in chloroform and concentrated invacuo, and then chromatographed on SiO₂ (40% hexanes in chloroform) toafford a dark purple powder as the title compound (1.08 g, 23%). ¹H NMR(500 MHz, CDCl₃, 298 K): 8.87 (m, 2H); 7.64 (m, 2H); 7.28 (m, 2H); 4.03(d, J=7.8 Hz, 4H); 1.91 (quintet, J=5.5 Hz, 2H); 1.30-1.21 (m, 32H);0.84 (m, 12H) ppm. ¹³C NMR (125 MHz, CDCl₃, 298 K): 161.75; 140.42;135.19; 130.50; 129.80; 128.39; 107.90; 46.15; 37.68; 31.74; 31.11;30.84; 29.66; 28.37; 26.14; 23.05; 22.62; 14.08; 14.03 ppm. HRMS(ESI-TOF-MS): m/z calcd for C₃₈H₅₆N₂O₂S₂[M+H]⁺ 637.3856. found 637.3857.

3,6-Bis(5-bromo-2-thienyl)-2,5-ditetradecylpyrrolo[3,4-c]pyrrole-1,4-dione(13a)

Protected from light, NBS (870 mg, 4.89 mmol) was added in portions to asolution of 14a (1.54 g, 2.22 mmol) in chloroform (60 mL) at roomtemperature. The reaction was stirred at room temperature overnight andpoured into 100 mL of methanol, and filtered with suction. The residuewas chromatographed on SiO₂ (30% hexanes in chloroform) to afford a darkpurple solid as the title compound (480 mg, 25%). ¹H NMR (500 MHz,CDCl₃, 298 K): 8.70 (d, J=4.2 Hz, 2H); 7.25 (d, J=4.2 Hz, 2H); 3.99 (t,J=7.8 Hz, 4H); 1.72 (quintet, J=7.5 Hz, 4H); 1.41 (m, 4H); 1.28 (m,40H); 0.88 (t, J=7.0 Hz, 6H) ppm. ¹³C NMR (125 MHz, CDCl₃, 298 K):161.03; 138.99; 135.37; 131.63; 131.07; 119.16; 107.75; 42.27; 31.91;29.96; 29.68; 29.64; 29.55; 29.47; 29.35; 29.18; 26.80; 22.69; 14.13ppm. HRMS (ESI-TOF-MS): m/z calcd for C₄₂H₆₂Br₂N₂O₂S₂ 848.2614. found848.2572.

3,6-Bis(5-bromo-2-thienyl)-2,5-bis(2-butyloctyl)pyrrolo[3,4-c]pyrrole-1,4-dione(13b)

Protected from light, NBS (268 mg, 1.51 mmol) was added in portions to asolution of 14b (436 mg, 0.684 mmol) in chloroform (20 mL) at roomtemperature. The reaction was stirred at room temperature overnight andpoured into 25 mL of methanol, and filtered with suction. The residuewas chromatographed on SiO₂ (40% hexanes in chloroform) to afford a darkpurple solid as the title compound (332 mg, 61%). ¹H NMR (500 MHz,CDCl₃, 298 K): 8.63 (d, J=4.2 Hz, 2H); 7.23 (d, J=4.2 Hz, 2H); 3.93 (d,J=7.8 Hz, 4H); 1.89 (quintet, J=5.5 Hz, 2H); 1.30-1.21 (m, 32H); 0.85(m, 12H) ppm. ¹³C NMR (125 MHz, CDCl₃, 298 K): 161.41; 139.40; 135.30;131.43; 131.11; 118.97; 107.99; 46.28; 37.70; 31.75; 31.07; 30.79;29.64; 28.33; 26.10; 23.02; 22.62; 14.09; 14.02 ppm. HRMS (ESI-TOF-MS):m/z calcd for C₃₈H₅₄Br₂N₂O₂S₂[M+H]⁺ 793.2066. found 793.2040.

3,6-Bis(5-bromo-2-thienyl)-2,5-bis(n-dodecyl)pyrrolo[3,4-c]pyrrole-1,4-dione(13c) and TDPP were synthesized according to the procedures described inTamayo, A. B. et al., J. Physc. Chem. C, 2008, 112, 15543-15552.

General procedure for synthesis of P4-P5:

The two monomers and Pd(PPh₃)₄(10 mol %) in anhydrous toluene (5 mL)were heated at 110° C. with stirring under nitrogen for three days.Afterward, end-capping reaction was performed by adding 10% of2-bromothiophene and 4 hours later 10% of 2-(tributylstannyl)thiophene.After 2 additional hours of stirring the reaction was allowed to cooldown to room temperature and dropped into methanol. The resulting solidswere subjected to Soxhlet extraction with acetone and hexanes, thendissolved in chloroform and chlorobenzene by Soxhlet extraction,precipitated in methanol, and filtered to give the copolymer as a purplesolid.

Polymer P4 a:

This product was obtained as a dark purple solid (73% yield). ¹H NMR(500 MHz, C₂D₂Cl₄, 403 K): 8.92 (br, 2H); 8.48 (br, 2H); 7.59 (br, 4H);4.54 (br, 4H); 4.22 (br, 4H); 2.13-0.96 (m, 108H) ppm. M_(n)=1.1 kg/mol,M_(w)=20.2 kg/mol, PDI=17.6. (Low M_(n) and high PDI may probably due toaggregation in trichlorobenzene solution even at high temperature of150° C.)

Polymer P4 b:

This product was obtained as a dark purple solid (60% yield). ¹H NMR(500 MHz, CDCl₃, 298 K): 9.10 (br, 2H); 8.04 (br, 2H); 7.06 (br, 4H);4.27 (br, 8H); 1.78-0.78 (m, 76H) ppm. M_(n)=13.6 kg/mol, M_(w)=79.6kg/mol, PDI=5.8.

Polymer P5 a:

This product was obtained as a dark purple solid (35% yield). ¹H NMR(500 MHz, C₂D₂Cl₄, 403 K): 8.90 (br, 2H); 7.74 (br, 2H); 7.54 (br, 2H);4.46 (br, 4H); 4.19 (br, 4H); 2.04-0.96 (m, 92H) ppm. M_(n)=2.7 kg/mol,M_(w)=35.7 kg/mol, PDI=13.3. (Low M_(n) and high PDI may probably due toaggregation in trichlorobenzene solution even at high temperature of150° C.)

Polymer P5 b:

This product was obtained as a dark purple solid (89% yield). ¹H NMR(500 MHz, CDCl₃, 298 K): 9.21 (br, 2H); 7.64 (br, 2H); 7.14 (br, 2H);4.15 (br, 8H); 1.85-0.80 (m, 76H) ppm. M_(n)=12.9 kg/mol, M_(w)=114.4kg/mol, PDI=8.8.

Example 4 Characterization of Polymer Semiconductors

UV/Vis absorption spectra of these polymers were collected in solutionand as thin films, and depicted in FIG. 5. The homopolymer P1 shows anabsorption peak at 347 nm and relatively weaker absorption around430-550 nm both in solution and as thin film. As the number of thiopheneincreases from 0 (P1), 1 (P2) to 2 (P3) in the repeating unit, theabsorption at low energy region (450-570 nm) is greatly enhanced withvibronic structure while the absorption peak of P1 at 347 nm getsrelatively weaker with a slight red shift to 367 nm. These observationscan be understood as a result of greater n-conjugation with enhancedorder which is also seen in regioregular polythiophenes. For P1-P3,absorption spectra of thin films are almost identical to those insolutions except for the larger peak at 441 nm in P2. Copolymer withTDPP (P4 and P5) have broad absorption up to >900 nm with absorptionmaxima around 760 nm due to their low band gap energy induced by thecopolymerization of electron-donating monomer (NDT and BDT) andelectron-deficient monomer (TDPP). In solution, polymers with branchedalkyl chains P4 b and P5 b have very similar absorption profiles, fromthe peak at 750 nm to the low energy end (˜865 nm). In contrast,polymers with linear alkyl chains P4 a and P5 a show broader absorptionthan P4 b and P5 b, respectively, to varying degrees. This suggests thatpolymers with linear alkyl chains aggregate to form strong π-πinteractions in solution, whereas those with branched chains do not.These observations have good agreement with the relatively poorsolubility of the polymers with linear chains. Thin film absorptionspectra of P4 a, P4 b and P5 b exhibit a shoulder at longer wavelength(around 840-900 nm) compared to those in solution, while P5 a havealmost identical spectra in this region between solution and thin film.This shoulder indicates greater organization in solid state for P4 a, P4b and P5 b compared to the solution phase and, on the other hand, P5 ahas similar degree of organization in solution and in solid state due tothe aggregation in solution as discussed above. Note that the absorptionshoulders of P5 a and P5 b are larger than those of P4 a and P4 b,indicating that BDT-based polymers have greater solid state orderingthan NDT-based polymers. The optical band gaps (E_(g) ^(opt)) of thepolymers are estimated from the red absorption edge and shown inTable 1. P1-P3 have band gaps in the range of 2.00-2.08 eV which aresimilar to the band gaps of BDT-based polymers previously reported inHou, J. et al., Macromolecules, 2008, 41, 6012-6018. As described above,P4 and P5 have a low band gap ranging from 1.33 to 1.38 eV due to theelectron-deficient feature of TDPP unit.

TABLE 1 Optical and Electrochemical Properties of P1-P5 E_(g) ^(opt)E_(ox) ^(onset) HOMO LUMO (eV)^(a) (eV)^(b) (eV)^(c) (eV)^(d) P1 2.080.54 −5.34 −3.26 P2 2.00 0.39 −5.19 −3.19 P3 2.04 0.46 −5.26 −3.22 P4a1.35 0.40 −5.20 −3.85 P4b 1.38 0.37 −5.17 −3.79 P5a 1.36 0.39 −5.19−3.83 P5b 1.33 0.48 −5.28 −3.95 ^(a)Optical band gap estimated fromabsorption edge of polymer films. ^(b)Electrochemically determined vsFc/Fc⁺. ^(c)HOMO = −(E_(ox) ^(onset) + 4.80). ^(d)LUMO = HOMO + E_(g)^(opt).

Example 5 Transistor Device Fabrication and Characterization

The charge transport properties of the present polymers were studiedusing bottom-gate top-contact OFET devices. The OFET devices werefabricated on either hexamethyldisilazane (HMDS)-treated oroctadecyltrichlorosilane (OTS)-treated p-doped Si (100) wafers with 300nm of thermally grown SiO₂ as dielectric layer. The capacitance of the300 nm SiO₂ gate insulator is ˜12 nF·cm⁻². Si wafers were cleaned bysonication in ethanol followed by 5 minutes of O₂ plasma.Trimethylsilation of the Si/SiO₂ surface was completed by exposure ofthe Si wafer to HMDS vapor in an air-free reaction vessel under N₂ atroom temperature. OTS-treatment of the Si/SiO₂ surface was completed byexposure of the Si wafer to a ethanol solution of OTS in an air-freereaction vessel under N₂ at room temperature. Polymer films weredeposited by spin-coating from 5 mg/mL or 10 mg/mL chloroform orchlorobenzene solutions in air. After spin-coating the semiconductorfilms of P1-P5, the films were annealed under vacuum at selectedtemperatures, as summarized in Table 2. To complete the devicefabrication, 50 nm of Au was thermally evaporated through a shadow maskat ˜1×10⁻⁶ Torr to yield the source and drain electrodes with a channellength and width of 100 and 5000 μm, respectively.

Device characterization was carried out either under vacuum or in air.

To allow comparison with other organic FETs, mobilities (μ) werecalculated by standard field effect transistor equations. In traditionalmetal-insulator-semiconductor FETs (MISFETs), there is typically alinear and saturated regime in the I_(DS) vs V_(DS) curves at differentV_(G) (where I_(DS) is the source-drain saturation current, V_(DS) isthe potential between the source and drain, and V_(G) is the gatevoltage). At large V_(DS), the current saturates and is given by:

(I _(DS))_(sat)=(WC _(i)/2L)μ(V _(G) −V _(t))²  (1)

where L and W are the device channel length and width, respectively,C_(i) is the capacitance of the oxide insulator (˜10 nF/cm² for ˜300 nmSiO₂), and V_(t) is the threshold voltage. Mobilities (μ) werecalculated in the saturation regime by rearranging equation (2):

μ_(sat)=(2I _(DS) L)/[WC _(i)(V _(G) −V _(t))²]  (2)

The threshold voltage (V_(t)) can be estimated as the X-axis interceptof the linear section of the plot of V_(G) versus (I_(DS))^(1/2) (atV_(DS)=−100 V).

TABLE 2 OFET Device Performances for P1-P5 Measured in AmbientConditions Substrate T_(annealing) μ_(h) V_(T) I_(on)/ treatment (° C.)(cm² V⁻¹ s⁻¹) (V) I_(off) P1^(a) HMDS 150 NA NA NA P2^(a) HMDS 150 2 ×10⁻⁵ −10 10⁴ P3^(a) HMDS 150 7 × 10⁻⁵ −14 10³ P4a OTS 240 0.1  −2 10⁴P4b OTS 200 0.04 0.1 10⁴ P5a OTS 240 0.06 4 10³ P5b OTS 240 4 × 10⁻³ 110⁴ ^(a)Measured under vacuum.

As shown in Table 3, the copolymers based on NDT and TDPP (P4 a-b)exhibited a p-type transistor operation with a high hole mobility up to0.1 cm²·V⁻¹·s⁻¹ and on/off ratio of 10⁴ with an optimized devicefabrication condition, whereas P2 and P3 exhibited a moderate holemobility of 2×10⁻⁵ cm²≦V⁻¹·s⁻¹ and 7×10⁻⁵ cm²≦V⁻¹·s⁻¹, respectively, andP1 did not show any transistor activity. Representative transfer andoutput plots of P4 a-based OFET devices are shown in FIG. 6. As theoptimized conditions for OFET device fabrication of P4 a-b, polymerfilms were deposited on OTS-treated substrate (contact angle ˜1030) andannealed at relatively high temperature of 200° C. or 240° C. OTS isselected as many high performance polymers based on TDPP have beenreported devices on OTS and higher mobility was observed with P4 b onOTS than on HMDS. The effect of alkoxy side chains on OFET performanceswas studied, and linear chains (P4 a) were found to give higherperformances (μ_(h)=0.1 cm²·V⁻¹·s⁻¹) than branched chains (P4 b: μ_(h)=0.04 cm²·V⁻¹·s⁻¹). Without wishing to be bound to any particulartheory, the higher performance with linear chains over branched chainscan be understood as a result of better organization and π-π stacking inthin films as shown in UV/Vis spectra. For a comparison between NDT andBDT, OFET devices with BDT-based polymers (P5 a-b) were fabricated andtested. The hole mobilities are 0.06 cm²·V⁻¹·s⁻¹ with P5 a and 4×10⁻³cm²·V⁻¹·s⁻¹ with P5 b, both lower than those of the correspondingNDT-based polymers P4 a (μ_(h)=0.1 cm²·V⁻¹·s⁻¹) and P4 b (μ_(h)=0.04cm²·V⁻¹·s⁻¹). Interestingly, as shown in the previous section, UV/Visspectra of NDT-based polymers have less pronounced shoulders near thered absorption edge compared to BDT-based polymers, which indicatessmaller degree of solid state ordering and thus is unfavorable foreffective intermolecular charge transport. Without wishing to be boundto any particular theory, it was speculated that other factors such asintrinsic properties of the monomers, or microstructural andmorphological characteristics of the polymer films in relation to theactual device architecture, could be affecting the device performances.Note that extended π-conjugation of NDT to promote intermolecularorbital overlap and/or the low reorganization energy in NDT corediscussed above could possibly be contributing the high mobility inNDT-based polymers.

X-ray diffraction (XRD) and atomic force microscopy (AFM) analyses wereconducted to evaluate the microstructures and morphologies of thepolymer films. XRD of P1 indicated low crystallinity compared to theother polymers and no significant grains were observed in the AFM image.This amorphous-like feature of P1 is unfavorable for effectiveintermolecular charge transport and should be one of the reasons for noactivity in OFET devices. The lack of order observed is probably due tothe high density of bulky octyldodecyl side chains within thehomopolymer. On the other hand, AFM images of P2 and P3 show noticeablegrains, which should favor intermolecular charge transport. However, thediffraction pattern in P2 film is almost featureless. By comparison, thebetter performing polymers P4 and P5 show more pronounced grains in AFMimages and larger diffraction peaks are observed compared to P2 and P3.These results show a good correlation between high degree of solid-stateordering and high performances in OFET devices. For the copolymers withTDPP (P4 a-b and P5 a-b), XRD confirmed the clear trend that linearchains promote crystallinity and would reasonably explain the OFETperformances of these polymers. The diffraction patterns of P4 a and P5a (with linear chains) show distinct peaks up to third order, whichindicates highly crystalline order in the polymer films, whereas only asingle peak is observed for P4 b and P5 b (with branched chains).Likewise, AFM images of polymers with linear chains present crystallinegrains with larger size than those of polymers with branched chains.These results are also in good agreement with the red-shift in UV/Visabsorption spectra with linear chains compared to those with branchedchains. As for comparison between BDT and NDT cores, BDT-based polymerP5 a and P5 b showed a similar diffraction pattern to the NDT-based P4 aand P4 b, respectively, although slight differences in the peak shapecould be noticed between P4 b and P5 b. On the other hand, AFM imagesshow significant differences in morphology between BDT-based andNDT-based polymers. BDT-based P5 b presents a fibril-like feature, whichcan be found in previously reported high-performance polymers, whereasNDT-based P4 b presents random-shaped grains. Without wishing to bebound to any particular theory, it was speculated that the fibrils of P5b do not have sufficient contacts between each other in terms of orbitaloverlap and thus inter-fibril charge carrier transport is not efficient.The slight difference in the peak shape of XRD between P4 b and P5 bcould be understood as a result of this morphology difference. The bestperforming NDT-based polymer with linear side chains, P4 a, presentssimilar grain shapes in its AFM image to P4 b (with branched chains) butmuch larger grain size. As discussed above, the large grain size andhigh crystallinity should contribute the high mobility with this polymer(μ_(h)=0.1 cm²·V⁻¹·s⁻¹). The analogous BDT-based polymer P5 a shows evenlarger grain size than P4 a, but the mobility (μ_(h)=0.06 cm²·V⁻¹·s⁻¹)is not as high as that of P4 a. There are noticeable gaps between grainsin its AFM image and these grain boundaries could possibly be limitingthe performance of this polymer. Note that it is difficult to quantifygrain boundaries from AFM images and NDT-based polymers P4 a and P4 bmight have similar degree of grain boundaries as P5 a and P5 b. However,P4 a exhibits a high mobility of 0.1 cm²·V⁻¹·s⁻¹, and even P4 b withrather low crystallinity and small grain size also exhibits a relativelyhigh mobility of 0.04 cm²·V⁻¹·s⁻¹. Without wishing to be bound to anyparticular theory, it is proposed that the extended π-conjugation of NDTcore provides a good chance of intermolecular orbital overlap even inless crystalline region such as grain boundaries.

Example 6 Synthesis and Characterization of NDT(TDPP)₂

TDPP-Br:

Protected from light, NBS (522 mg, 2.93 mmol) in CHCl₃ (50 mL) was addedto a solution of TDPP (1.54 g, 2.93 mmol) in CHCl₃ (100 mL) at 0° C.over 6 h. The reaction was stirred at ambient temperature overnight andthe solvent was removed under reduced pressure. The residue waschromatographed on SiO₂ (hexanes-CHCl₃, gradient from 9:1 to 3:2) toafford the title compound as a purple solid (934 mg, 53%). ¹H NMR (500MHz, CDCl₃, 298 K): ∂=8.92 (d, J=3.5 Hz, 1H), 8.65 (d, J=4.0 Hz, 1H),7.65 (d, J=5.0 Hz, 1H), 7.28 (dd, J=5.0 Hz, 4.0 Hz, 1H), 7.23 (d, J=4.0Hz, 1H), 4.07-3.90 (m, 4H), 1.90-1.82 (m, 2H), 1.38-1.22 (m, 16H),0.91-0.82 (m, 12H) ppm. ¹³C NMR (125 MHz, CDCl₃, 298 K): ∂=161.6, 161.5,140.9, 138.9, 135.6, 135.1, 131.4, 131.2, 130.9, 129.7, 128.5, 118.6,108.1, 107.7, 45.9, 45.9, 39.1, 39.0, 30.1, 30.1, 28.3, 23.5, 23.5,23.0, 23.0, 14.0, 10.4 ppm. HRMS (ESI-TOF-MS): m/z calcd forC₃₀H₄₀BrN₂O₂S₂ [M+H]+ 603.1714. found 603.1715. Anal. Calcd forC₃₀H₃₉BrN₂O₂S₂: C, 59.69; H, 6.51. Found: C, 59.72; H, 6.45.

NDT(TDPP)₂:

Dry toluene (10 mL) and dry DMF (2 mL) were added to compound 5c (80.4mg, 0.0978 mmol), TDPP-Br (147 mg, 0.243 mmol) and Pd(PPh₃)₄ (11.5 mg,0.00996 mmol). The reaction was heated to 120° C. and stirred for 24 h,then poured into MeOH (150 mL) and stirred for 20 min. The resultingprecipitate was collected by vacuum filtration and chromatographed onSiO₂ (hexanes-CHCl₃, gradient from 30:70 to 0:100) to afford the titlecompound as a shiny, bronze-colored solid (120 mg, 80%). ¹H NMR (500MHz, CDCl₃, 298 K): ∂=8.97 (d, J=4.5 Hz, 2H), 8.95 (d, J=4.0 Hz, 2H),8.35 (s, 2H), 7.65-7.64 (m, 4H), 7.50 (d, J=4.0 Hz, 2H), 7.29 (d, J=4.5Hz, 2H), 4.30 (d, J=5.5 Hz, 4H), 4.14-4.02 (m, 8H), 2.02-1.20 (m, 54H),1.12 (t, J=7.5 Hz, 6H), 1.01 (t, J=7.0 Hz, 6H), 0.97-0.86 (m, 24H) ppm.¹³C NMR (125 MHz, CDCl₃, 298 K): ∂=161.6, 161.5, 149.2, 142.1, 140.3,140.2, 139.3, 136.9, 136.5, 135.5, 130.7, 129.8, 129.6, 128.5, 126.5,126.4, 125.7, 121.7, 111.3, 108.5, 108.1, 75.6, 45.91, 40.8, 39.3, 39.1,30.4, 30.4, 30.2, 29.7, 29.2, 28.6, 28.3, 23.9, 23.7, 23.5, 23.2, 23.2,23.1, 14.3, 14.2, 14.1, 11.4, 10.6, 10.5 ppm. MS (ESI): m/z calcd forC₉₀H₁₁₇N₄O₆S₆ [M+H]+ 1541.7. found 1541.5. Anal. Calcd forC₉₀H₁₁₆N₄O₆S₆: C, 70.09; H, 7.58; N, 3.63. Found: C, 70.19; H, 7.55; N,3.54.

NDT(TDPP)₂ optical spectra in chloroform (FIG. 7A) reveal λ_(max)=624 nmwith a very high molar absorption coefficient of 1.1×10⁵ L·mol⁻¹·cm¹. Aspun cast film from CHCl₃ (10 mg·mL⁻¹) exhibits a red-shifted λ_(max) of676 nm, suggesting molecular aggregation and coplanarity in the solidstate. The absorption onset for the spun cast film is 720 nm,corresponding to an optical band gap of ˜1.72 eV. Cyclic voltammetry wasused to estimate the HOMO energy. The onset of oxidation at 0.60 V,versus ferrocene/ferrocenium, yields a HOMO energy of −5.40 eV, and fromthe optical band gap and measured HOMO, the LUMO energy is estimated tobe −3.68 eV.

FIG. 7B shows wide-angle X-ray diffraction (WAXRD) data using standardθ-2θ techniques for a drop cast NDT(TDPP)₂ film on a HMDS-treatedSi/SiO₂ substrate. The reflections at 2θ=5.69° and 11.39° correspond tod-spacings of 15.53 and 7.77 angstroms and indicate long-range order,possibly with edge-on molecular orientation.

Example 7 Fabrication and Characterization of OFETs and OPVs Based onNDT(TDPP)

Bottom-gate/top-contact OFETs were fabricated on HMDS-treated p-doped Si(001) wafers with 300 nm thermally grown SiO₂ as dielectric layer asdescribed in Example 5. The semiconductor layer was deposited by placing5 drops of NDT(TDPP)₂ or NDT(TDPP)₂.PC₆₁BM (w:w) at 10 mg·mL⁻¹ and 20mg·mL⁻¹, respectively, from anhydrous chloroform on an HMDS-treatedwafer. After 30 seconds, the remaining solution not dried off was flungoff by hand. After the semiconductor was deposited, the device wasannealed at 110° C. To complete the device fabrication, 50 nm of Au wasthermally evaporated through a shadow mask at ˜1×10⁻⁶ Torr to yield thesource and drain electrodes with a channel length and width of 100 and5000 μm, respectively. Device characterization was carried out in air.Table 3 summarizes the top-contact OFET performance of drop-castNDT(TDPP)₂ and various blend ratios between NDT(TDPP)₂ and PC₆₁BM onHMDS-treated Si/SiO₂ wafer annealed at 110° C., measured in air.

TABLE 3 OFET Device Performances for NDT(TDPP)₂ and NDT(TDPP)₂•PC₆₁BMBlend Ratio μ_(h) V_(T) I_(on)/ [D:A] (cm² V⁻¹ s⁻¹) (V) I_(off) 2.3:1 3× 10⁻³ −19.5 8 × 10² 1.5:1 3 × 10⁻³ −19.5 5 × 10²   1:1 4 × 10⁻³ −17.5 5× 10² NDT(TDPP)₂ 7 × 10⁻³ −14.9 4 × 10³

The output and transfer plots of a top-contact OFET from a drop castNDT(TDPP)₂ film on a Si/SiO₂/HDMS substrate (FIGS. 7C-7D) indicatep-type behavior with μ_(h)=7×10⁻³ cm²·V⁻¹ s⁻¹, among the highestmobilities reported for a solution-processed small-molecule OPV electrondonor. OFETs of NDT(TDPP)₂.PC₆₁BM blends exhibit only slightly lowerμ_(h) values, suggesting the formation of BHJ domains by the presence ofPC₆₁BM within the NDT(TDPP)₂ network.

OPV devices were fabricated and tested using various blend ratiosbetween NDT(TDPP)₂ and PC₆₁BM. Patterned ITO-coated glass (Thin FilmDevice, Inc.), with a resistivity of <10Ω/□ and a thickness of 280 nmwas cleaned in sequential sonications at 50° C. in soap/DI water, DIwater, methanol, isopropanol, and acetone for 30 min. After the finalsonication step, substrates were blown dry with a stream of N₂ gas. ITOsubstrates were then treated for 30 minutes in a UV/O₃ oven (JelightCo.). PEDOT:PSS (Clevios P VP Al 4083) was then spun-cast at 5000 rpmfor 30 sec and subsequently annealed at 150° C. for 15 min. Immediatelyfollowing PEDOT:PSS annealing, samples were blown with a stream of N₂gas to drive off moisture. Samples were then transferred to a N₂-filledglove box for active layer and top contact deposition. Active layerscontaining donor NDT(TDPP)₂ and acceptor PC₆₁BM (>99.5% pure, AmericanDye Source) were formulated inside the glove box in various ratios (w:w)at a total concentration of 20 mg·mL⁻¹ in distilled chloroform. Activelayer solutions were then allowed to stir at 600-800 rpm for 1.5 h at40° C. The active layer solutions were spun-cast at 4000 rpm for 15 secto afford an active layer thickness of ˜75 nm (by AFM). Samples werethen either thermally annealed at various temperatures (60-150° C.) for10 min on a temperature-controlled hot plate or left as cast. To finishdevice fabrication, LiF(1.0 nm)/Al(100 nm) were thermal evaporated,sequentially, at a base pressure of ˜4.0×10⁻⁶ torr. The top Alelectrodes were then encapsulated with epoxy and a glass slide beforetesting. J-V characteristics were measured using the methods statedpreviously. Each pixel of the device was carefully masked with blackrubber to prevent parasitic charge leakage and inaccurate electrodeoverlap. Each substrate had 4 pixels with a defined area of 0.06 cm².Table 4 summarizes the J-V and EQE response of various blend ratiosbetween NDT(TDPP)₂ and PC₆₁BM annealed at 110° C. for 10 minutes.

TABLE 4 J-V and EQE response of OPV devices based on NDT(TDPP)₂•PC₆₁BMblends J_(SC) J_(SC) Blend Ratio V_(OC) [mA/cm²] FF PCE EQE_(λ-570)[mA/cm²] [D:A] [mV] measured (%) (%) (%) calculated^(a) 2.3:1 870 8 402.9 45 8 1.5:1 840 11 43 4.1 66 11   1:1 800 9 38 2.9 54 9^(a)Calculated J_(SC) from integrating entire EQE spectrum.

Previous small-molecule bulk-heterojunction (BHJ) solar cells utilizingPC₆₁BM as the electron acceptor fullerene have yielded PCEs no higherthan 3.7%. The PCE of 4.1% for the NDT(TDPP)₂:PC₆₁BM (1.5:1, w/w) devicereported here is believed to be the highest reported PCE for aPC₆₁BM-based small-molecule device and among the highest for anysolution-processed small-molecule OPV.

Example 8 Preparation of P(NDT(2EH)-TPD)

Compound 14 was synthesized according to the literature procedure (Zouet al., J. Am. Chem. Soc. (2010) 132, 5330-5331). Compound 11 (94.0 mg,0.114 mmol), TPD monomer 14 (54.7 mg, 0.114 mmol), the catalystPd(PPh₃)₄ (13.5 mg, 0.0116 mmol), and toluene (15 ml) were combinedunder N₂ atmosphere and the reaction mixture was stirred at 110° C. for3 days. 2-Bromothiophene (0.1 ml) was added to the reaction and thereaction was refluxed for 12 hours, then cooled and concentrated invacuo to the amount of ˜1 ml. The concentrated solution was dropped intomethanol (100 ml) and the precipitate was then collected via filtration.The black solid was Soxhlet extracted by acetone (1 day), hexane (1 day)and toluene (1 day) in this order. The toluene extract was concentratedand reprecipitation in methanol afforded a dark brown solid (43.1 mg).

The present teachings encompass embodiments in other specific formswithout departing from the spirit or essential characteristics thereof.The foregoing embodiments are therefore to be considered in all respectsillustrative rather than limiting on the present teachings describedherein. Scope of the present invention is thus indicated by the appendedclaims rather than by the foregoing description, and all changes thatcome within the meaning and range of equivalency of the claims areintended to be embraced therein.

We claim:
 1. An electronic, optical or optoelectronic device comprisinga molecular semiconductor component, the molecular semiconductorcomponent comprising a compound having formula (II):

wherein: R¹ and R² independently are a C₁₋₂₀ alkyl group or a C₁₋₂₀haloalkyl group; Ar¹, Ar², Ar³, and Ar⁴ independently are an optionallysubstituted C₆₋₁₄ aryl group or an optionally substituted 5-14 memberedheteroaryl group; π, at each occurrence, independently is an optionallysubstituted polycyclic aryl or heteroaryl group; m¹, m², m³ and m⁴independently are 1, 2, 3 or 4; and p is 0 or
 1. 2. The device of claim1, wherein Ar¹, Ar², Ar³, and Ar⁴ independently are an optionallysubstituted thienyl group or an optionally substituted bicyclicheteroaryl group comprising a thienyl group fused with a 5-memberedheteroaryl group.
 3. The device of claim 1, wherein the compound has theformula:

wherein: R³, R⁴, R⁵, and R⁶, at each occurrence, independently areselected from H and R⁷, wherein R⁷, at each occurrence, independently isselected from a halogen, CN, a C₁₋₂₀ alkyl group, a C₁₋₂₀ haloalkylgroup, a C₁₋₂₀ alkoxy group, and a C₁₋₂₀ alkylthio group; and R¹, R², π,and p are as defined in claim
 1. 4. The device of claim 3, wherein pis
 1. 5. The device of claim 4, wherein π is an optionally substitutedheteroaryl group represented by a formula selected from:

wherein Het, at each occurrence, is a monocyclic moiety including atleast one heteroatom in its ring and optionally substituted with 1-2 R¹⁰groups, wherein R⁸, R⁹, and R¹⁰ independently can be H or R⁷, whereinR⁷, at each occurrence, independently is selected from a halogen, CN, aC₁₋₂₀ alkyl group, a C₁₋₂₀ haloalkyl group, a C₁₋₂₀ alkoxy group, and aC₁₋₂₀ alkylthio group.
 6. The device of claim 1, wherein the compoundis:

wherein R¹, R² and R¹⁰ independently are a C₁₋₂₀ alkyl group.
 7. Acompound having formula (II):

wherein: R¹ and R² independently are a C₁₋₂₀ alkyl group or a C₁₋₂₀haloalkyl group; Ar¹, Ar², Ar³, and Ar⁴ independently are an optionallysubstituted C₆₋₁₄ aryl group or an optionally substituted 5-14 memberedheteroaryl group; π, at each occurrence, independently is an optionallysubstituted polycyclic aryl or heteroaryl group; m¹, m², m³ and m⁴independently are 1, 2, 3 or 4; and p is 0 or 1.